The Deep Web - What it is, tips for dealing with it, and how to locate its content Finding Scholarly Content on the Web

The deep web is usually defined as the content on the Web not accessible through a search on general search engines. This content is sometimes also referred to as the hidden or invisible web.
The Web is a complex entity that contains information from a variety of source types and includes an evolving mix of different file types and media. It is much more than static, self-contained Web pages. In fact, the part of the Web that is not static, and is served dynamically "on the fly," is far larger than the static documents that many associate with the Web.
The concept of the deep Web is becoming more complex as search engines have found ways to integrate deep Web content into their central search function. This includes everything from airline flights to news to stock quotations to addresses to maps to activities on Facebook accounts. In the screenshot below, notice the various deep Web sources offered by Google, including images, maps, news, video, shopping, scholarly content, blogs, and so on. However, even a search engine as far-reaching as Google provides access to only a very small part of the deep Web.

Content on the deep Web

When we refer to the deep Web, we are usually talking about the following:

• The content of databases. Databases contain information stored in tables created by such programs as Access, Oracle, SQL Server, and MySQL. (There are other types of databases, but we will focus on database tables for the sake of simplicity.) Information stored in databases is accessible only by query. In other words, the database must somehow be searched and the data retrieved and then displayed on a Web page. This is distinct from static, self-contained Web pages, which can be accessed directly. A significant amount of valuable information on the Web is generated from databases.
• Non-text files such as multimedia, images, software, and documents in formats such as Portable Document Format (PDF) and Microsoft Word. For example, see Digital Image Resources on the Deep Web for a good indication of what is out there for images.
• Content available on sites protected by passwords or other restrictions. Some of this is fee-based content, such as subscription content paid for by libraries or private companies and available to their users based on various authentication schemes.
• Special content not presented as Web pages, such as full text articles and books
• Dynamically-changing, updated content, such as news and airline flights

This is usually the basic,"traditional" list. In these days of the social Web, let's consider adding new content to our list of deep Web sources. For example:

• Blog postings
• Comments
• Discussions and other communication activities on social networking sites, for example Facebook and Twitter
• Bookmarks and citations stored on social bookmarking sites

As you can see, based on these few examples, the deep Web is expanding.

Tips for dealing with deep Web content

• Vertical search can solve some of the problems with the deep Web. With vertical search, you can query a collection of data focused on a specific topic, industry, type of content, geographical location, language, file type, Web site, piece of data, and so on. For example, consider MedNar and PubMed to search for medical topics. On the social Web, there are search engines for blogs, RSS feeds, Twitter content, and so on.
  Tip! See the tutorial on Vertical Search Engines for more information.
• Use a general search engine to locate a vertical search engine. For example, a Google search on "stock market search" will retrieve sites that allow you to search for current stock prices, market news, etc. This may be thought of as split level searching. For the first level, search for the database site. For the second level, go to the site and search the database itself for the information you want.
• A number of general search engines will search the deep Web for related content subsequent to an initial search. For example, try a search on Google for "World Trade Center" and select the Images tab. This will retrieve many pages of images of the World Trade Center. Look for this type of feature on other search engines.
• Try to figure out which kind of information might be stored in a database.. There is no general rule. But think about large listings of things with a common theme. A few examples of databased content include:
• phone books
• "people finders" such as lists of professionals such as doctors or lawyers
• patents
• laws
• dictionary definitions
• items for sale in a Web store or on Web-based auctions
• digital exhibits
• images and multimedia
• full text articles and books
• Information that is new and dynamically changing in content will appear on the deep Web. Look to the deep Web for late breaking items, such as:
• news
• job postings
• available airline flights, hotel rooms
• stock and bond prices, market averages
• The social Web often jumps on a late-breaking situation with news items and commentary. Blogs, Facebook, Twitter, and other social networking environments sometimes get out the word before more traditional sources.
• Topical coverage on the deep Web is extremely varied. This presents a challenge, since it is impossible to anticipate exactly what might turn up.

Best Bet Search Tips - A summary of best bet tips for creating searches on Web search engines

Here is a quick summary of best bet tips for putting together a search on a Web search engine.
~ Most search engines default to Boolean AND logic. To create a search that will retrieve Web pages containing all of your search terms, type the words with a space in between them. Example: bears hibernation
~ Include synonyms or alternate spellings in your search statements and connect these words with Boolean OR logic. OR logic will allow you to retrieve documents containing one or more of your search terms. Search engines are not consistent in the way they want an OR search to be typed out (for example, Google requires that OR be capitalized), so it's usually best to fill out the form on the advanced search page and let the search engine do the rest. Example: college OR university
~ For a Boolean NOT search, place a minus sign (-) in front of the word you want to exclude from your search results. Example: apple -computer
To summarize:

These search statements	Will retrieve...
World War I AND World War II	pages containing both these terms
World War I OR World War II	pages containing at least one of these terms
World War I NOT World War II	pages containing the term World War I but not also the term World War II

~ Surround a phrase with quotation marks. Example: "freedom of the press" This will also work with individual words that you want to search exactly as you have typed them. Example: "president"
~ Use the advanced search page when you want to do a focused search. The advanced search page is a good way to limit your results in various ways, including words in the title, date, language, file type, site, etc. The advanced search page is great to try out because it shows you the types of searches the search engine can do for you.
~ If your search results look too general for what you want, try these techniques:

• Add another concept with AND logic
• Use vocabulary that is specific to your topic, e.g., "Honda" rather than "cars"
• Narrow your search to various fields, for example, words in the title, date, site, etc., easy to do on an advanced search page
• Use the Boolean NOT to keep out pages containing words you don't want

~ If your search results look too narrow or limited for what you want, try these techniques:

• Drop off the least important concept(s) to broaden your subject
• Use more general vocabulary
• Add alternate terms or spellings for individual concepts and connect with the Boolean OR
• Don't use field searching

~ Finally, keep this general search advice in mind:

• If you're not sure how to use a particular search engine, read the Help pages. With just a few minutes of effort, you can be on your way to conducting an effective search.
• Check your spelling.
• Take advantage of capitalization if the search engine is case sensitive. Hint: Google is not case sensitive.
• If your results are not satisfactory, repeat the search using alternative words.

Basic Search Techniques - how-to guide for creating AND, OR, NOT, phrase, and field searches on Web search engines.

This tutorial is a how-to guide for creating AND, OR, NOT, phrase, and field searches on Web search engines.
We'll be using Google as an example. Keep in mind that the illustrated searches will work on most general search engines on the Web.
Tip! Before you read this tutorial, be sure that you understand the basics of Boolean logic. Check out Boolean Searching on the Internet. If you take the time to understand the basics of Boolean logic, you will have a better chance of search success.

Before you search, make a plan!

Putting together a search is a three-step process.
1. Identify your concepts
When planning your search, break down your topic into its separate concepts. Let's say you're interested in the effects of global warming on crops. In this case, you have two concepts: GLOBAL WARMING and CROPS.
2. Make a list of search terms for each concept
Once you have identified your concepts, list the terms which describe each concept. Some concepts may have only one term, while others may have many.

global warming
greenhouse effect
greenhouse gases
climate change

crops
crop yields
crop production
food supply

These lists are a suggestion. Depending on the focus of your search, there may be other terms more suited to what you're looking for.
3. Specify the logical relationships among your search terms
Once you know the words you want to search, you need to establish the logical relationships among them using Boolean logic: AND, OR, NOT.
To keep things simple, you don't need to use all the words you've compiled in a single search. The words are there to help you experiment with different searches until you find the results you want.
TIP! There are also optional things you can do to focus a search. One useful option is known as field searching, and is covered later on in this tutorial.

Boolean AND search

Let's start with a very simple two-word search. In this type of search, we want Web pages that contain both of our search terms. This is Boolean AND logic. This is probably the most common type of search that people want to do.
With most general search engines on the Web, including Google, all you need to do is type your search terms in the input box and the terms will be searched using Boolean AND logic. In other words, Boolean AND is the default logic.
In our example, we're asking for documents that contain the words rain and snow. To do this, we simply type the two words into the search box with a space between them.

Try this search yourself! You should get results that are similar to the ones shown in the screenshot below.

Notice how both words appear in the results. This is exactly what we wanted.

At one time, a variant of an AND search was the plus sign (+). For example, +rain +snow guaranteed that the two words would appear in your search results. Most search engines, including Google, have dropped the use of the plus sign. Google's plus sign was useful. It told Google to turn off the option to search for word variants, spelling variants, similar terms, etc. Now you can create the same kind of precision search by selecting the "Verbatim" option under "More search tools" on the left sidebar. The Verbatim option guarantees that your search terms will be searched exactly as you have typed them.

Boolean OR search

What if we want results that include either the word rain or the word snow? This calls for Boolean OR logic. With OR logic, we're asking for one word, or the other word, or both. An easy way to use OR logic is to use an advanced search page. Most search engines have such an option and it's very useful.
Notice how the two search terms were typed into the line one or more of these words.

And the results are in, as you can see in the screenshot below - all 551,000,000 of them! The search results include pages with just the word rain or just the word snow, exactly as we wanted. Farther down in the results will be documents containing both words - the overlap in the Venn diagram that you learned about in Boolean Searching on the Internet.
Notice that Google has translated this search into its own syntax: rain OR snow. Google requires that the word OR be typed in CAPITAL LETTERS. So do some other search engines. Since this may not be easy to remember, it's best to use the advanced search page and let the search engine do the rest.

An OR search is usually used to search for synonyms, for example, global warming OR climate change.

Boolean NOT search

Sometimes you want to retrieve documents that do not contain a particular word. This can help when associated words are not really relevant and can muddy the focus of your results. To do this, place a minus sign (-) in front of the word you want to exclude.
Let's go back to our rain-snow example. In this case, we want documents that contain the word rain, but not the word snow. So, we've placed the minus sign immediately in front of the word snow: rain -snow.

Try this search yourself! You should get results that are similar to the ones shown in the screenshot below.

Beware! (1) You may end out excluding relevant pages with this technique. Proceed with care. (2) You many also end out with results that you don't want. When you look at the results screen above, you see that the term rain has different meanings. To search for the weather phenomenon of rain, it would be a good idea to add a semantically meaningful word such as weather, storm or the like. The more specific your terminology, the better your results will be.

Combined Boolean AND, OR search

Sometimes you need a search that is more complex than a single AND or OR search. It is possible to combine both types of Boolean logic in the same search. Most search engines offer a way to do this. Given the variety in search engine syntax, it is best to try this type of search using an advanced search page. Advanced search pages are great for...advanced types of searches!
Let's say you want to learn about the behavior of cats. You believe that using both the words cats and felines will help you get more results than using just one of these words. The example below shows you how to do this type of search on an advanced search page.

Phrase Search and Exact Word Search

Some words naturally appear in the context of a phrase, for example, freedom of the press. To search on phrases in most search engines, simply enclose the phrase within quotes: "freedom of the press".

Try this search yourself! You should get results that are similar to the ones shown in the screenshot below.

Phrases are especially important when there are stop words in your search. These are "little" words such as a, and, the, in, it, etc. Most search engines tend to ignore these words. If you want to be sure they are included in your search results, enclose them with the rest of your search within quotes.
In fact, whenever you want to search any word exactly as you have typed it, enclose the word within quotes: "president". In many search engines, this will ensure that only this exact word will be searched. The search engine will not look for any variations, such as presidents, presidential, etc.

Field Search

Field searching is an optional way to focus your search results. With general search engines, you're searching the full text of many millions of pages, and field searching can help you retrieve results that may be more manageable. For example, you can search for words that appear within a particular Web site, within the URL (Web address), in the page title, and so on. The exact technique for doing this can differ among search engines, so be sure to check out the Help pages before proceeding. Let's consider a couple of examples on Google.

Title field

A title search can bring you more relevant results than merely searching for words that appear anywhere on the Web page. It's more likely that a document that contains your search words in the title will be more relevant that a document that does not. For this reason, many search engines use title words as an important way of ranking search results in order of their relevancy.
Let's look for Web pages that contain our search terms in the page title. Again, we'll use Google to try this out, revisiting its advanced search page. Here, you need to open up the page to display all its options by clicking on the plus sign (+) near the bottom of the page next to the options for Date, usage rights, numeric range, and more.
Where your keywords show up gives you the option to select in the title of the page. Let's search for hurricane caribbean deaths.

Notice that Google translated this search into allintitle: hurricane caribbean deaths. If you memorize this search syntax, you can conduct this search from Google's main search page.

Site field

Searching on the site field is another useful way of finding relevant results. In this case, you search on the top-level and second-level domain names together, and then use AND logic to add topical words to your search.
You can read about domain structures in the tutorial A Basic Guide to the World Wide Web. Briefly, to take an example shown below: "nasa" is a second-level domain, and "gov" is a top-level domain.
Examples of sites:

nasa.gov
mit.edu
microsoft.com

Let's look at an example of a site search. Let's say you are searching for information about spacewalks conducted by NASA. Try this: spacewalks site:nasa.gov. This search will limit your results to pages on the NASA Web site.

Try this search yourself! You should get results that are similar to the ones shown in the screenshot below.

Notice that all the results come from the site nasa.gov. You can also go to the advanced search page on Google to conduct this search.

Natural language search

A few search engines encourage you to type your search as a "normal" question or sentence, rather than concern yourself with Boolean logic. This is sometimes known as a natural language search. On these engines, a variety of sophisticated techniques are working behind the scenes to analyze your search and return relevant results. Hakia is a good example of this type of engine. Give it a try and see what you think.

And there's So Much More!

In this tutorial, we've explored some basic search techniques. These should cover many of your search needs. But there is much more. Many search engines offer a variety of other options to help you retrieve the results you want. Google, in particular, offers all kinds of specialty searches. Check out the Google page Search Features for the details.
For example:

You want...	Method	Type this search	Result
Synonyms	Tilde sign	˜proof	proof, proofs, evidence, etc.
Fill in the blank	Asterisk	Shakespeare works *	Shakespeare works, Folger Shakespeare Library, Shakespeare Bookshelf, etc.

By now, you may have noticed that you can use either the main search box or the advanced search page. It's a great idea to check out the advanced search page on the search engines that you visit. Not only will your searches be easier to create, but you'll be able to put together searches that will help to focus your results.

SEARCH TECHNIQUES - Boolean Searching on the Internet

A Primer in Boolean Logic

Boolean logic allows you to combine words and phrases into search statements to retrieve documents from searchable databases. This tutorial will show you how to utilize Boolean logic to search the Internet.
The Internet is a vast computer database. As such, its contents must be searched according to the rules of computer database searching. Much database searching is based on the principles of Boolean logic. Boolean logic refers to the logical relationship among search terms, and is named for the British-born Irish mathematician George Boole.
On Internet search engines, the options for constructing logical relationships among search terms often modify the traditional practice of Boolean searching. This will be covered in the section below, Boolean Searching on the Internet.
Boolean logic consists of three logical operators:

• OR
• AND
• NOT

Each operator can be visually described by using Venn diagrams, as shown below.

OR logic

college OR university

Question: I would like information about college.

• In this search, we will retrieve records in which AT LEAST ONE of the search terms is present. We are searching on the terms college and also university since documents containing either of these words might be relevant.
• This is illustrated by:
• the shaded circle with the word college representing all the records that contain the word "college"
• the shaded circle with the word university representing all the records that contain the word "university"
• the shaded overlap area representing all the records that contain both "college" and "university"

OR logic is most commonly used to search for synonymous terms or concepts.
Here is an example of how OR logic works:

Search terms	Results
college	396,482
university	590,791
college OR university	819,214

OR logic collates the results to retrieve all the unique records containing one term, the other term, or both of them.
The more terms or concepts we combine in a search with OR logic, the more results we will retrieve.

college OR university OR campus

For example:

Search terms	Results
college	396,482
university	590,791
college OR university	819,214
college OR university OR campus	929,677

AND logic

poverty AND crime

Question: I'm interested in the relationship between poverty and crime.

• In this search, we retrieve records in which BOTH of the search terms are present
• This is illustrated by the shaded area overlapping the two circles representing all the records that contain both the word "poverty" and the word "crime"
• Notice how we do not retrieve any records with only "poverty" or only "crime"

Here is an example of how AND logic works:

Search terms	Results
poverty	76,342
crime	348,252
poverty AND crime	12,998

The more terms or concepts we combine in a search with AND logic, the fewer results we will retrieve.

poverty AND crime AND gender

For example:

Search terms	Results
poverty	76,342
crime	348,252
poverty AND crime	12,998
poverty AND crime AND gender	1,220

NOT logic

cats NOT dogs

Question: I want information about cats, but I don't want to see anything about dogs.

• In this search, we retrieve records in which ONLY ONE of the terms is present, the one we have selected by our search
• This is illustrated by the shaded area with the word cats representing all the records containing the word "cats"
• No records are retrieved in the area overlapping the two circles where the word "dogs" appears, even if the word "cats" appears there too

Here is an example of how NOT logic works:

Search terms	Results
cats	86,747
dogs	130,424
cats NOT dogs	65,223

NOT logic excludes records from your search results. Be careful when you use NOT: the term you do want may be present in an important way in documents that also contain the word you wish to avoid. For example, consider a Web page that includes the statement that " cats are smarter than dogs." The search illustrated above would exclude this document from your results.

Combined AND and OR logic

Question: I want information about the behavior of cats.
Search: behavior AND (cats OR felines)
You can combine both AND and OR logic in a single search, as shown above.
The use of parentheses in this search is known as forcing the order of processing. In this case, we surround the OR words with parentheses so that the search engine will process the two related terms as a unit. The search engine will use AND logic to combine this result with the second concept. Using this method, we are assured that the semantically-related OR terms are kept together as a logical unit.

Boolean Searching on the Internet

When you use an Internet search engine, the use of Boolean logic may be manifested in three distinct ways:

1. Full Boolean logic with the use of the logical operators
2. Implied Boolean logic with keyword searching
3. Boolean logic using search form terminology

1. Full Boolean logic with the use of the logical operators

This is classic Boolean searching. However, few search engines nowadays offer the option to do full Boolean searching with the use of the logical operators. It is more common for them to offer simpler methods of constructing search statements, specifically implied Boolean logic and search form terminology. These methods are covered below.
If you want to construct searches using Boolean logical operators, you will need to experiment with search engines and see what happens. You can try some of the search statements shown below. Keep in mind that the search engine might require that the Boolean operators be typed in CAPITAL LETTERS. Don't forget that most search engines provide help pages that explain the kind of searching you can do on their sites.
Question: I need information about cats.

Boolean logic: OR
Search: cats OR felines

Question: I'm interested in dyslexia in adults.

Boolean logic: AND
Search: dyslexia AND adults

Question: I'm interested in radiation, but not nuclear radiation.

Boolean logic: NOT
Search: radiation NOT nuclear

Question: I want to learn about cat behavior.

Boolean logic: AND, OR
Search: behavior cats OR felines

The last example is a tricky search on most search engines. It combines implied AND logic - designated by the space between the word "behavior" and "cats" - with the use of the Boolean OR operator. You can give this search a try, but the search engine might not process it as you intended. The safest way to conduct this type of search is to use the advanced search page available on most search engine sites. This will be shown in option #3 below (search form terminology).

2. Implied Boolean logic with keyword searching

keyword searching refers to a search type in which you enter words in a search box representing the concepts you wish to retrieve. Boolean operators are not used.
implied boolean logic refers to a search in which symbols are used to represent Boolean logical operators. In this type of search, the absence of a symbol is also significant, as the space between keywords defaults to either OR logic or AND logic.
Nowadays, virtually all general search engines on the Web default to AND logic. In other words, when you type words into a search box and generate your search, Boolean AND logic is going on behind the scenes.
Implied Boolean logic is so common on Web search engines that it can be considered a de facto standard.
Question: I need information about cats.

Boolean logic: OR
Search: [no implied Boolean logic is available]

There are probably no general search engines on the Web that interpret the space between keywords as the Boolean OR. Rather, the space between keywords is interpreted as AND. To do an OR search, choose either option #1 above (full Boolean logic) or option #3 below (search form terminology).
Question: I'm interested in dyslexia in adults.

Boolean logic: AND
Search: dyslexia  adults

Question: I'm interested in radiation, but not nuclear radiation.

Boolean logic: NOT
Search: radiation  -nuclear

Notice the minus sign (-) in front of the word "nuclear".
Question: I want to learn about cat behavior.

Boolean logic: AND, OR
Search: [no implied Boolean logic is available]

3. Boolean logic using search form terminology

Many search engines offer an advanced search page with a search form which allows you to choose the Boolean operators from a menu. Usually the logical operator is expressed with substitute terminology rather than with the operator itself.
Question: I need information about cats

Boolean logic: OR
Search: Any of the words/At least one of the words/Should contain the words

Question: I'm interested in dyslexia in adults.

Boolean logic: AND
Search: All of these words/Must contain the words

Question: I'm interested in radiation, but not nuclear radiation.

Boolean logic: NOT
Search: Must not contain the words/Should not contain the words

Question: I want to learn about cat behavior.

Boolean logic: AND, OR
Search: Combine options if the form allows multiple search logic, as in the example below.

Quick Comparison Chart:
Full Boolean vs. Implied Boolean vs. Search Form

	Full Boolean	Implied Boolean	Search Form Terminology
OR	college or university	[rarely available]	any of the words at least one of the words should contain the words
AND	poverty and crime	poverty   crime	all of these words must contain the words
NOT	cats not dogs	cats   -dogs	must not contain the words should not contain the words

RSS Basics - Whats is RSS used for?

RSS is a feed format that is used to distribute frequently-published content. The feed format is a standardized subset up the mark-up language known as XML. The resulting feeds can be pushed to RSS readers and Web pages.
The initials RSS can stand for different things, including Rich Site Summary or Really Simple Syndication. RSS content is often referred to as syndicated content because of its wide distribution. Users can subscribe to the RSS feeds of their choice, and then have access to the updated information as it comes in.
The presence of an RSS feed is often signaled by an orange icon of some type. Two examples are shown here.
RSS is an important part of the participatory Web. It has been said that RSS is the "glue" that holds the social Web together. You will encounter RSS in all sorts of places and used for all kinds of purposes. Wherever content is frequently added, you will probably find an RSS feed. This is because many sites on the social Web automatically create RSS feeds and add to the feed as you add content. If you want to keep up with the latest contributions by people on the social Web, reading RSS feeds is one of the best ways to do it.

Reading RSS feeds

To experience RSS, you first need to subscribe to the feed using an rss reader, or aggregator. This is software that displays new items posted to your feed subscriptions and stores the old updates. It is similar to e-mail software, except that the incoming items are derived from RSS feeds.
There are all kinds of RSS readers. Popular Web browsers offer integrated RSS readers. You can also download a reader to your computer or mobile device. Or, you can use an RSS reader on the Web, for example the Google Reader. The advantage here is that you can access your RSS feeds from any computer that is connected to the Web.
Subscribing to an RSS feed is as simple as adding its address to your reader's subscription list. Below is an example from the Google Reader.

A useful list of RSS readers is available on the site RSS Specifications.
tip! RSS feeds can be imported into Web pages. You might be looking at a "typical" Web page without realizing that the content is coming from an RSS feed. There are various programming techniques that make this possible. Or, you can use one of the many user-friendly services on the Web such as RSS2HTML.

Sources of RSS feeds

As noted earlier, RSS is especially popular for distributing news updates and for announcing new content added to the social Web. Various media types can also be updated via RSS feed, including podcasts. A few examples are shown below.
If you click on any of the feed links below, you will be taking the first step toward subscribing to the feed. After clicking, you will be prompted to save the feed to your browser's feed reader, if you have one. Otherwise, you can click on the feed link with your right mouse button and select the option to Copy Link Location. You can then paste the location into the feed reader of your choice.

News updates: Environment news from The New York Times
Blogs: postings and comments from the blog Librarians Matter
Documents on social bookmarking sites: Google-related bookmarks on CiteULike
Tagged items on photo sharing sites: "nature" tag on Flickr
Twitter updates: Al Gore

Creating RSS feeds

How do you create an RSS feed? Well, usually you don't have to lift a finger. As noted above, creating RSS feeds is an automatic feature of many sites on the social Web. For example, if you maintain a blog, the blog software will create the feed.
If you want to create an RSS feed on your own, it isn't too difficult. Some people manually create feeds to distribute their podcasts. Below is a snippet from an RSS template for creating a podcast suitable for uploading to iTunes. Notice how much metadata the feed includes - data about the data included in the feed.

The Web and You: A Guide to Participation

In 2006, Time magazine named You as the Person of the Year with the comment: "Yes, you. You control the Information Age. Welcome to your world."
This tutorial will explain how you - yes, you - can participate in and therefore control your experience of the Web. The Web allows anyone with an Internet connection to join in. (Unfortunately, some of this capability is blocked in certain countries.) With the proper tools, you can create content either alone or collaboratively, share your content, and comment on the content of others. There are various terms used to describe this phenomenon, including web 2.0, the social web, the read-write web. The topic is huge. This tutorial is intended as a brief introduction to the lay of the land.
It's interesting to watch as the content of the social Web is entering the mainstream of the Web experience. For example, blog posts can be found in search engine results. The search engine Bing indexes Twitter content in order to provide up-to-the-minute results, and Facebook status updates are in the works. This brings up the importance of the social Web to the real-time web. It is becoming increasingly important to the development of the Web to present real-time, or near real-time, content.
A large factor in interacting with the Web is having access to the Web at any time and any place. The Web and its functionalities are becoming increasingly mobile. While laptop computers have been around for years, the focus now is on cell phones, tablet computers and other portable devices connected to the Web. The iPhone is just one example of a device that allows people to take the Web with them wherever they go to access Web sites, social networks, search engines, and location-based information. Mobile devices can keep us connected to the networked world with ever-expanding capabilities.
tip! To keep up with the latest developments, check out the suggested sources on Keeping Current.

First, a word about security and safety

The Web has sometimes been referred to as the Wild Wild Web. As the Web becomes more open to user interaction, dangers can be lurking. Computer viruses of various types, identity theft, bogus e-mail messsages and Web sites, and predators, are just a few of the dangers you might encounter.
When you interact with strangers on the Web, proceed with caution. Don't automatically trust what you see or who you encounter. Be careful about what you share about yourself, and where you share it. There are many sites on the Web that can help you become aware of potential dangers and provide guidelines for dealing with them. For an example, check out the useful Internet Safety Project.

Social networking sites

social networking sites are online communities in which members interact. In fact, everything covered in this tutorial involves social networking of some sort. A site that specializes in social networking is focused on making connections among its users. The activities may be limited to one activity or interest, such as sharing videos, to multiple activities such as creating a personal profile, posting your current activity or state of mind, making "friends", engaging in discussions, joining groups, sending messages, sharing photos, and so on. Social networking can involve individuals or institutions, and can be used for recreational, informational, academic, and professional purposes.
Examples: Facebook, Google +, LinkedIn, MySpace, FriendFeed, LibraryThing, Digg
It is becoming easier to share content from around the Web. Let's say you have read an article that you want to share on your Facebook account. Web sites, especially blog and news sites, sometimes offer an easy way to post this content to the social networking site of which you are a member. Here is an example of the many sharing options featured on a technology blog. If you have an account on any of these services, you can share the posting there with just a few clicks. The ShareThis application is shown in the example below.

Sometimes Web site owners offer a few buttons from the most popular social networks. Recommendation buttons for Facebook, Google+ and Twitter are showing up all across the Web. Two of the buttons are displayed here.

Blogs, tweets and the phenomenon of comments

A blog is a journal entry system organized around postings about which readers can comment. Entries are usually organized with the most recent postings first. The word "blog" comes from "Weblog" because a blog consists of a Web-based signed and dated log of individual postings. Blogs often focus on personal narratives or opinion and are usually maintained by single individuals. However, there are also plenty of blogs maintained by groups of people who share the same interests or expertise.
Examples: TechCrunch, The New Old Age, Climate411
The social nature of blogs comes from reader responses to the blog author's postings. These are known as comments. Readers can respond not only to postings, but also to their comments, resulting in a lively conversation. Most comments are written in text. However, video comments are also possible. For example, the TechCrunch blog uses Seesmic for this purpose.

Anyone can start a blog for free. Take a look at Wordpress and Blogger for a couple of examples. If you rent space on a Web server, you can download blog software and run your own customized blog. Some excellent blog software is available at no cost, including WordPress and MovableType.
Technorati and Google Blog Search are two useful search engines for locating content posted to blogs.
microblogging is also popular. This is exemplified by Twitter. With Twitter, you can create an account and blog in spurts of up to 140 characters. Also, excerpted postings or headlines from "regular" blogs can be sent automatically to your Twitter account. For an example, visit the TechCrunch page on Twitter. With a Twitter account, you can choose to "follow" other members and receive their "tweets" on your own page. Twitter is used by the famous and non-famous alike for recreational, professional, commercial, and informational purposes. If you want to know what's happening right now, check out Twitter.
Twitter search is one of many sites that provides a searchable real-time look at up-to-the-minute tweets. Below is an example of a few tweets.

As with many other social networking sites, a universe of creative tools have been built by the Web community to enhance the Twitter experience. For example, check out 99 Essential Twitter Tools and Applications from Smashing Magazine.
The phenomenon of blogs has helped to advance the practice of commenting across the Web. In fact, one hallmark of the social Web is the option for public comment. For example, you can comment on YouTube videos and Flickr photos. Many news sites offer their readers the option to comment on stories. Commenting is showing up in all kinds of Web sites and in all kinds of contexts, so be on the lookout for opportunities.
The nature of any comment you make is up to you. Comments can range from polite to insulting and anything in between. Below is an example of comments from the news sharing site iReport.

Wikis

A wiki is a publishing platform on which many people can contribute new content and revise existing content. The content benefits from the collective knowledge of the contributors, so wikis can be very beneficial for group projects. Some businesses and organizations use wikis to maintain documents. Wikis allow visitors to view the history of page edits. For this reason, wikis are an excellent option for hosting documents that need ongoing edits or updates. Entire books can be publised on a wiki; for examples, visit Wikibooks.
As with blogs, anyone can start a wiki for free. Two options are PBwiki and Wikidot.

Examples: Wikipedia, Digital Research Tools, EduTech Wiki

tip! Some people get confused about the differences between blogs and wikis. For a useful discussion, see the Blogs and Wikis page at the University at Albany Libraries.

Social bookmarking sites

social bookmarking allows you to save articles, news stories, blog postings, etc. from the Web and organize them into folders and/or tags. (See below for a discussion about tags.) The addition of new bookmarks can often be followed with an RSS feed; see the tutorial RSS Basics for more information.

A benefit of social bookmarking is the fact that your bookmarks are online, rather than on your local computer. With Web-based bookmarking, you can access your bookmarks from anywhere. The aspect of public sharing is also important.
Examples: Delicious, CiteULike, Connotea, StumbleUpon

Multimedia

Multimedia is a prominent part of the social Web. Users create audio and video files and share them with the public. Photo sharing is also a popular activity on the social Web. There are also TV broadcasts, radio stations, and Web cams set up by users. On many multimedia sharing sites, users are invited to post comments. For more details about this phenomenon, see the tutorial on Multimedia.
Examples: Flickr, YouTube, Hulu, iReport

Real-time chat, texting and phone calls

Real-time communication on the social Web is big. Here we'll briefly cover chat/instant messaging and Web-based phone calls.
The terms chat and instant messaging (im) are sometimes used interchangeably, and refer to the real-time communication between people through typing and other means. With chat and instant messaging, a user on the Web can contact another user currently logged in to the same service and start a conversation. Multiple people can join a chat, and everyone can see each new message as it comes in. Chat is sometimes included as a feature of a Web site, where users can log into the chat room to exchange comments and information about the topic in the particular room.
You can download IM software onto your computer, or use the chat function sometimes offered on the software creator's Web site. Most famous is America Online's (AOL) Instant Messenger, but there are many others. Pidgin and Meebo are examples of chat programs that integrate the chat functionality of several individual services. Some chat software can be embedded on your Web page so that your visitors can easily chat with you. To the right is a screen shot of the embedded Meebo widget.
Chat has evolved into texting. The formal name for this is Short Message Service, or SMS. With texting, you use a mobile device to send short text messages to another device. The rise in popularity of texting has followed the trajectory of the rise in popularity of mobile phones. Nowadays many people use texting rather than make a phone call or send an e-mail.
video chat is also a popular communication option. Why settle for audio or text when you can see the person you're communicating with? All you need is a webcam and video chat software. For example, people who use Google's GMail can engage in voice and video chat. Skype is such popular video chat software that the name has become a verb: "Do you want to Skype today?" Enhanced programs offer a combination of text chat, voice, and video communication. This capability allows people to conference and collaborate in real time. Such features as whiteboarding, document sharing, and collaborative browsing can also be available. This is often referred to as conferencing software.
Examples: Skype, Meebo, AOL Instant Messenger (AIM), Yahoo! Messenger, Pidgin
Finally, you can also make phone calls on the Web. Besides video chat, Skype allows you to make calls to regular and mobile phones. Google offers free phone calls.

Tags

How can you organize your content on the social Web? One way is with tags. People who create or share content on social networking sites often have the option of assigning topic words to their content. These are known as tags. Tags can help organize content into concepts or categories. With so much information on the Web, topical labeling can be useful. Once tags have been assigned, users can then click on a tag of interest and see all the content assigned to that tag.
The choice of tag words is up to the creator. This is one of the drawbacks of tags: different people use different tags to describe similar content. However, it is possible for people to get together and agree on common tags to describe similar content.
The use of tags is showing up in many contexts, as many social networking sites offer its members the option to assign tags to their content. You, too, can be a part of the tagging phenomenon! Tags are especially popular on blogs and social bookmarking sites. The online reference management tool Zotero allows users to organize citations with tags. Also check out the display of popular tags on Flickr. This type of display is known as a tag cloud. The larger the font assigned to the tag, the more often the tag has been assigned. The tag cloud below is derived from a technology blog.

There are many ways to implement tags. Check out The Tagging Toolbox: 30+ Tagging Tools from the blog Mashable. Here you'll find tools for creating, displaying, and viewing tags, both online and offline.

Multimedia on the Web

Today's Web presents a diversified multimedia experience. In fact, the Web has become a broadcast medium, offering live TV and radio, pre-recorded video, photos, images, and animations. Expect to encounter multimedia just about anywhere on the Web. This tutorial presents a brief overview.

Plugins, media players, and multimedia types

plugins and media players are software programs that allow you to experience multimedia on the Web. These terms are sometimes used interchangeably. File formats requiring this software are known as MIME types. MIME stands for Multimedia Internet Mail Extension, and was originally developed to help e-mail software handle a variety of binary (non-textual) file attachments. The use of MIME has expanded to the Web. For example, the basic MIME type handled by Web browsers is text/html associated with the file extention .html. MIME types area also used to process multimedia on the Web. A few examples:

• Jpeg photo: image/jpeg
• MPEG video: video/mpeg
• Quicktime movie: video/quicktime
• MP3 audio: audio/x-mpeg-3
• Flash presentation: application/x-shockwave-flash

Nowadays, many personal computers come pre-loaded with plugins and media players. This is an acknowledgement of the importance of the Web multimedia experience. If your computer doesn't have a particular piece of software, it can be easily obtained from the Web site of the company that created it. Downloading is easy and instructions are usually provided.
plugins are software programs that work with your Web browser to display multimedia. When your browser encounters a multimedia file, it hands off the data to the plugin to play or display the file. Working in conjunction with plugins, browsers can offer a seamless multimedia experience. The plugins needed to experience Web multimedia are available for free.
A common plugin used on the Web is the Adobe Reader. This software allows you to view documents created in Adobe's Portable Document Format (PDF). These documents are the MIME type "application/pdf" and are associated with the file extension .pdf. A PDF is a type of image file. When the Adobe Reader has been downloaded to your computer, the software will open and display the file when you click on its link on a Web page. Try viewing this PDF document from the U. S. Census Bureau. Sometimes a Web page will display the official PDF icon to alert you that the file is in PDF format.
media players are software programs that can play audio and video files, both on and off the Web. The concept of streaming media is important to understanding how media can be delivered on the Web. With streaming technology, audio or video files are played as they are downloading, or streaming, into your computer. Sometimes a small wait, called buffering, is necessary before the file begins to play. Extensive pre-recorded files such as interviews, lectures, televised video clips, podcasts, and music work very well with these players. They can also be used for real-time radio and TV, including Web-only TV. Popular media players include the Windows Media Player, RealPlayer, QuickTime Player, and Flash Player.

Audio

Audio files, including music, are an important part of the Web experience. Listening to music on the Web is a popular pastime. Audio files of many types are supported by the Web with the appropriate players. The MP3 file format probably the most popular option for audio files.
MP3 files are also the source of podcasts. These are audio files distributed through RSS feeds, though the term is sometimes also used to describe video programming (or vodcast). You can subscribe to a podcast's RSS feed, and listen to the podcast series, with a special type of player called a podcatcher. A podcatcher can be either available on the Web or downloaded to your computer like any other plugin. iTunes can serve as a podcatcher. Keep in mind that you can often listen to a podcast on the originating site. For an example, visit NYTimes.com Podcasts.
Want to create your own podcast? Fondren Library at Rice University offers useful instructions in their tutorial Podcasting Howtos.
tip! Podcast series are available via RSS feed. To learn about RSS, visit the tutorial RSS Basics.
Thousands of radio stations broadcast live on the Web. Just use a search engine to locate a station's Web site, and follow the links to the live broadcast. Visit this page for an example of one radio station's live broadcasts.

Video

Streaming video is the backbone of live and pre-recorded broadcasting on the Web. YouTube is one of the most popular sites on the Web for pre-recorded video. Real-time professional or personal broadcasts are also very popular.
The Web is a medium for exchanging information among professionals. A live professional broadcast from a conference, company, or institution is sometimes referred to as a webcast. A variation on this is a webinar, a seminar broadcast on the Web.
To watch video discussions by experts in their fields, take a look at:

• Academic Earth, a collection of free video lectures by top scholars
• BigThink, where experts discuss current events
• Bloggingheads.tv, where academics, journalists, and others have two-way conversations, or diavlogs, on substantive topics
• Hulu, a site offering TV broadcasts and movies
• iTunes U, which offers free lectures from a handful of universities
• WebMedia: Special Events at Princeton University, offering archived speeches and conferences

live cams and live tv are a big part of the real-time video experience available on the Web. Live cams are video cameras that send their data in real time to a Web server. These cams may appear in all kinds of locations, both serious and whimsical: an office, on top of a building, a scenic locale, a special event, a fish tank, and so on. Live cams are stationary and only broadcast what is in their line of sight. Moving video takes live broadcasting to the next level: TV on the Web. Some people wear portable cameras and allow the public to observe their lives - an intense form of reality TV. Justin.tv was a pioneer in this type of live broadcasting. Other people broadcast their involvement in specific topics, such as cooking or technology. Check out Blip.tv and Ustream for examples.
Live TV broadcasts abound on the Web. As with radio stations mentioned above, use a search engine to locate a station's Web site and follow the links to the live broadcast. There are also plenty of pre-recorded network TV shows available on the Web. Check out Hulu for an example of a site that hosts this type of content.

Embedded media

As you browse the Web, you can experience multimedia on the sites of the people who sponsor or create the broadcasts. There are also aggregator sites you can visit, including Flickr and YouTube.
It's also possible to embed multimedia on your own Web pages. The capacity for unlimited distribution is a major reason why multimedia on the Web has become so popular. Also, it's quite easy to do. In most cases, embedding a media file is just a matter of copying code and pasting it onto your Web page. The two examples below took only a few minutes to complete. Both require the Flash player (MIME type of application/x-shockwave-flash).
Here is an embedded video from YouTube.

Here is a Picasa slideshow from my 2008 high school reunion. You might enjoy looking at my photos of the historic Emma Willard School in Troy, NY.

For advice on embedding media (and other file types, too), check out How To Embed Almost Anything in your Website from the technology blog Digital Inspiration.
tip! The phenomenon of embedded media is related to the concept of widgets. A widget is a snippet of a program running on another site that can be embedded on your own Web page. Check out Widgetbox to get an idea of some widgets you might want to try.

Understanding the World Wide Web

This tutorial covers the basics of the World Wide Web, focusing on its technical aspects. After all, the Web is a technological phenomenon. Therefore it's useful to understand some of the fundamentals of how it works.
The world wide web is a system of Internet servers that supports hypertext and multimedia to access several Internet protocols on a single interface. The World Wide Web is often abbreviated as the web or www.
The World Wide Web was developed in 1989 by Tim Berners-Lee of the European Particle Physics Lab (CERN) in Switzerland. The initial purpose of the Web was to use networked hypertext to facilitate communication among its members, who were located in several countries. Word was soon spread beyond CERN, and a rapid growth in the number of both developers and users ensued. In addition to hypertext, the Web began to incorporate graphics, video, and sound. The use of the Web has reached global proportions and has become a defining element of human culture in an amazingly short period of time.
In order for the Web to be accessible to anyone, certain agreed-upon standards must be followed in the creation and delivery of its content. An organization leading the efforts to standardize the Web is the World Wide Web (W3C) Consortium. Take a look at the W3C Consortium Web site to get an idea of its activities. A lot of the material is technical because, after all, the Web is a technical phenomenon.

Protocols of the Web

The surface simplicity of the Web comes from the fact that many individual protocols can be contained within a single Web site. internet protocols are sets of rules that allow for intermachine communication on the Internet. These are a few of the protocols you can experience on the Web:
HTTP (HyperText Transfer Protocol): transmits hyptertext over networks. This is the protocol of the Web.

E-mail (Simple Mail Transport Protocol or SMTP): distributes e-mail messages and attached files to one or more electronic mailboxes.

FTP (File Transfer Protocol): transfers files between an FTP server and a computer, for example, to download software.

VoIP (Voice over Internet Protocol): allows delivery of voice communications over IP networks, for example, phone calls.

The Web provides a single, graphical interface for accessing these and other protocols. This creates a convenient and user-friendly environment. Once upon a time, it was necessary to know how to use protocols within separate, command-level environments. This meant you needed to know the text commands and type them out to make things happen. The Web is much easier, since it gathers these protocols together into a unified graphical system. Because of this feature, and because of the Web's ability to work with multimedia and advanced programming languages, the Web is by far the most popular component of the Internet.

Hypertext and links: the motion of the Web

The operation of the Web relies primarily on hypertext as its means of information retrieval. HyperText is a document containing words that connect to other documents. These words are called links and are selectable by the user. A single hypertext document can contain links to many documents. In the context of the Web, words or graphics may serve as links to other documents, images, video, and sound. Links may or may not follow a logical path, as each connection is created by the author of the source document. Overall, the Web contains a complex virtual web of connections among a vast number of documents, images, videos, and sounds.
Producing hypertext for the Web is accomplished by creating documents with a language called hypertext markup language, or html. With HTML, tags are placed within the text to accomplish document formatting, visual features such as font size, italics and bold, and the creation of hypertext links.

<p> This is a paragraph that shows the underlying HTML code. <strong>This sentence is rendered in bold text</strong>. <em>This sentence is rendered in italic text.</em> </p>

HTML is an evolving language, with new tags being added as each upgrade of the language is developed and released. Nowadays, design features are often separated from the content of the HTML page and placed into cascading style sheets (css). This practice has several advantages, including the fact that an external style sheet can centrally control the design of multiple pages. The World Wide Web Consortium (W3C), led by Web founder Tim Berners-Lee, coordinates the efforts of standardizing HTML. The W3C now calls the language XHTML and considers it to be an application of the XML language standard.

Pages on the Web

The backbone of the World Wide Web are its files, called pages or Web pages, containing information and links to resources - both text and multimedia - throughout the Internet.
Web pages can be created by user activity. For example, if you visit a Web search engine and enter keywords on the topic of your choice, a page will be created containing the results of your search. In fact, a growing amount of information found on the Web today is served from databases, creating temporary Web pages "on the fly" in response to user searches. You can see an example of such a page below, taken from the search engine Hakia. This page only exists as a result of a search.

Access to Web pages can be accomplished in all sorts of ways, including:

1. Entering a Web address into your browser and retrieving a page directly
2. Browsing through sites and selecting links to move from one page to another both within and beyond the site
3. Doing a search on a search engine to retrieve pages on the topic of your choice (See: The World of Search Engines)
4. Searching through directories containing links to organized collections of Web pages (See: The World of Subject Directories)
5. Clicking on links within e-mail messages
6. Using apps on social networking sites or your mobile phone to access Web and other online content
7. Retrieving updates via RSS feeds and clicking on links within these feeds (See: RSS Basics)

Retrieving files on the Web: the URL and Domain Name System

url stands for uniform resource locator. The URL specifies the Internet address of a file stored on a host computer, or server, connected to the Internet. Web browsers use the URL to retrieve the file from the server. This file is downloaded to the user's computer, or client, and displayed on the monitor connected to the machine. Because of this relationship between clients and servers, the Web is a client-server network.
Underlying the functionality of a URL is a base numeric address that points to the computer that hosts the file. This numeric address is called the ip (internet protocol) address. The host portion of a URL is translated into its corresponding IP address using the domain name system (dns). The DNS is a worldwide system of servers that stores location pointers to the computers that host networked files. Since numeric strings are difficult for humans to use, alphneumeric addresses are employed by users. Once the translation is made by the DNS, the browser can contact the server and ask for the specific file designated in the URL.
For example, the DNS translates www.microsoft.com into the IP address 207.46.19.254.
Anatomy of a URL
Every file on the Internet, no matter what its protocol, has a unique URL. Each URL points to a specific file located in a specific directory on the host machine. This is the format of a URL:

protocol://host/path/filename

For example, this is a URL from the site of the U.S. Senate of a live video stream sent by a camera pointed at the U.S. Capitol:

http://www.senate.gov/general/capcam.htm

This URL is typical of addresses hosted in domains in the United States. The structure of this URL is shown below.

1. Protocol: http
2. Host computer name: www
3. Second-level domain name: senate
4. Top-level domain name: gov
5. Directory name: general
6. File name: capcam.htm

Note how much information about the content of the file is present in this well-constructed URL.
Several generic top-level domains (gTLDs) are common in the United States:

com	commercial enterprise
edu	educational institution
gov	U.S. government entity
mil	U.S. military entity
net	network access provder
org	usually nonprofit organizations

In addition, dozens of domain names have been assigned to identify and locate files stored on servers in countries around the world. These are referred to as country codes, and have been standardized by the International Standards Organization as ISO 3166. For example:

ch	Switzerland
de	Germany
jp	Japan
uk	United Kingdom

Additional top-level domain names were approved in 2000 by the Internet Corporation for Assigned Names and Numbers (ICANN): .biz, .museum, .info, .pro (for professionals) .name (for individuals), .aero (for the aerospace industry), and .coop (for cooperatives). Unconventional domain names have been marketed outside of the system, for example, .tv for sites that offer content similar to television broadcasts. In 2011, ICANN decided to open up domain names without restriction, including in any language or written script. The cost of establishing and maintaining a new name is quite expensive - $185,000 for the application fee alone - so the actual effect of this change will be limited.
As the technology of the Web evolves, URLs have become more complex. This is especially the case when content is retrieved from databases and served onto Web pages. The resulting URLs can have a variety of elaborate structures, for example,

http://spills.incidentnews.gov/incidentnews/FMPro?-db=images&-Format=maps.htm
&SpillLink=8&Subject=Waterway%20Closure%20Map&-SortField=EntryDate&
-SortOrder=descend&-SortField=EntryTime&-SortOrder=descend&-Token=8&
-Max=20&-Find

The first part of this URL looks familiar. What follows are search elements that query the database and determine the order of the results. As a growing number of databases serve content to the Web, these types of URLs are appearing more commonly in your browser's address window.

Programming languages and environments

The use of programming languages beyond HTML extend the capabilities of the Web. They are used to write software, process Web forms, fetch and display data, and perform all kinds of advanced functions. It is difficult to talk about these languages without getting into too much technical jargon, but here is an attempt. What follows is a brief guide to some of the more common languages in use on the Web today.
CGI (Common Gateway Interface) refers to a specification by which programs can communicate with a Web server. A CGI program, or script, is any program designed to process data that conforms to the CGI specification. The program can be written in any programming language, including C, Perl, and Visual Basic Script (VBScript). In the early days of the Web, CGI scripts were commonly used to process a form on a Web page. Perl is popular with Google, and is also the language of the Movable Type blog platform.
Active Server Pages (ASP): Developed by Microsoft, ASP is a programming environment that processes scripts on a Web server. The programming language VBScript is often used for the scripting. Lightweight programs can be written with this language. Active Server Pages end in the file extension .asp. For an example, check out Databases and Indexes at the University at Albany Libraries.
.NET framework: Also developed by Microsoft, this development framework is a more powerful one than ASP for writing applications for the Web. Programming languages include C+ and VB.Net. ASP.Net is a related environment, producing pages with the file extensions .aspx. The Microsoft site is a good example of a site created with the .NET framework.
PHP: This is another server-based language. It is frequently the language used to write open source (e.g., nonprofit, community-created) programs found on the Web, including MediaWiki (the software that runs the Wikipedia), and the popular blog software WordPress. While PHP functionality can be installed on Windows servers, it is native to the Linux server environment and commonly used there.
Java/Java Applets: Java is a programming language similar to C++. Developed by Sun Microsystems, the aim of Java is to create programs that will be platform independent. The Java motto is, "Write once, run anywhere." A perfect Java program should work equally well on a Windows, Apple, Unix, or Linux server, and so on, without any additional programming. This goal has yet to be realized. Java can be used to write applications for both Web and non-Web use.
Web-based Java applications are usually in the form of Java servlets. These are small Java programs fetched from within a Web page that can be downloaded from a server and run on a Java-compatible Web browser. A Web page that links to a Java servlet has the file extension .jsp.
JavaScript is a very popular programming language created by Netscape Communications. Small programs written in this language are embedded within a Web page, or fetched externally from within the page, to enhance the page's functionality. Examples of JavaScript include drop-down menus, image displays, and mouse-over interactions. The drop-down menus on the site of the UCLA Library shown below are a good example: when you hover your mouse over the menu item, a set of sub-menus opens up below.

XML: XML (eXtensible Markup Language) is a mark-up language that enables Web designers to create customized tags to provide functionality not available with HTML alone. XML is a language of data structure and exchange, and allows developers to separate form from content. With XML, the same content can be formatted for multiple applications. In May 1999, the W3 Consortium announced that HTML 4.0 has been recast as an XML application called XHTML.
AJAX stands for Asynchronous JavaScript and XML. This langauge is used to create interactive Web applications. Its premise is that it sends data to the browser behind the scenes, so that when it is time to view the information, it is already "there." Google Maps is a well-known example of AJAX. A different kind of example can be found with SurfWax LookAhead, an RSS search tool that retrieves feeds as you type your search.
SQL (Structured Query Language): This is a language that focuses on extracting data from databases. Programmers write statements called queries that retrieve data from the tables in the database. Some Web sites are created extensively or entirely from data stored in database tables. You can often tell that a SQL query has produced data on a page by the presence of a question mark (?) and a record number in the URL, as the example below illustrates.

Mashups

Programs on the Web can be flexible. Sometimes they are combined with each other to form ehanced presentations. These are known as mashups.
A mashup is a Web application or Web page that combines data from two or more external sources. Mashups give you access in one place to information available in multiple places.
There are all kinds of mashups on the Web. One example is Earthquakes In The Last week, a mashup derived from data from the U.S. Geological Survey along with Google Maps. Another is Mashpedia, a mashup of the Wikipedia encylopedia along with current information gathered from the social Web.

Last but not least: Applications (apps)

Applications, commonly called apps, are small programs that run within various online environments. These programs allow you to enjoy functionalities that enhance your experience within that environment.
Social networking sites often make use of apps. For example, Facebook is well-known for featuring thousands of apps created by Facebook or outside developers. These apps allow you to play games, shop, form issues-based communities, find family or classmates, etc.
Mobile phones are another environment within which apps are both popular and useful. In fact, no decent mobile phone these days comes without the option to add apps. A good example is the iPhone, which offers hundreds of thousands of apps in all sorts of areas, from work and education to travel, lifestyle, entertainment, and so on. Also take a look at the Android Market site to browse the apps available for the Droid phone. It is safe to say that apps make the mobile phone what it is today.
Apps are a very fast-growing area of the networked experience. Some observers believe that apps will be a focus of developments in the online world in the coming years.