apples AND oranges

Use an AND between search terms when you need to narrow your search. The AND indicates that only those Web pages having both words in them will be retrieved.

apples OR oranges

An OR between search terms will make your resulting set larger. When you use OR, Web pages that have either term will be retrieved.

apples AND NOT oranges

The NOT operator is used when a term needs to be excluded. In this example, Web pages with both apples and oranges in them would not be retrieved.

apples AND (oranges OR tangerines)

This example shows nested Boolean logic. Use this logic when you need to include ANDs and ORs in one search statement. In the example above, the parentheses indicate that oranges or tangerines will be processed first, and that this result will be combined with apples. If the parentheses were not there, the search engine would perform the search from left to right. All pages with both the words apples and oranges would be found first, and then all pages with the word tangerines would be included.

Implied Boolean operators, or pseudo-Boolean operators, are shortcuts to typing AND and NOT. In most search engines that support this feature, you would type "+" before a word or phrase that must appear in the document and "-" before a word or phrase that must not appear in a document.

A phrase is a string of words that must appear next to each other. Global warming is a phrase, as is chronic fatigue syndrome. Use phrase-searching capability when the words you are searching for must appear next to each other and must appear in the order in which you typed them. Most search engines require double quotation marks to differentiate a phrase from words searched by themselves

Proximity operators are words such as near or within. For example, you are trying to find information on the effects of chlorofluorocarbons on global warming. You might want to retrieve results that have the word chlorofluorocarbons very close to the phrase global warming.

Truncation is the process of looking for multiple forms of a word. Some search engines refer to truncation as stemming. For example, if you were researching postmodern art, you might want to retrieve all the records that had the root word postmodern, as well as postmodernist and postmodernism. Most search engines support truncation by allowing you to place an asterisk (*) at the end of the root word. For example, in this case we would type postmodern*.

Using wildcards allows you to search for words that have most of the word in common, except for maybe a letter or two. For example, we might want to search for both woman and women. Instead of typing woman or women, we could place a wildcard character (most often an asterisk) to replace the fourth letter. It would look like this: wom*n.