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.