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Research 101: Boolean Operators

Information on the research process.

Boolean Operators

Boolean operators or connectors are tools that allow you to narrow or broaden your search.

Using AND between your search terms will narrow your search.  For example, searching elections AND contributors will find resources with both terms, giving you more specific results. You can keep adding terms with AND to conduct more narrow searches: elections AND contributors AND special interests AND federal law.

Using OR between your search terms will broaden your search.  The OR operator is useful when a term has a frequently used synonym. Examples: Political Action Committee OR PAC; college OR university, corn OR maize. Conducting a search using the OR operator will find resources with either term, giving more results.

Using NOT between your search terms will narrow your search. NOT allows you to exclude a word or phrase from your search. For example, elections NOT presidential will find resources on elections (local, Senate, etc.) but exclude information about Presidential elections.

Combining Search Options

You may want to combine the search strategies discussed above.  When using a combination of Boolean operators use parentheses to delineate the search. 

(PAC OR political action committee) and campaign* and financ*

Default Settings

If you type in your search terms and do not enter any Boolean operators the library database will usually search for all your terms. So you are by default conducting an AND search.


Using a wildcard symbol allows you to search for alternative spellings within a word.

Wildcards can replace one character.  For example, wom?n searches women and woman.

A different symbol may be used to replace more than one letter or to accommodate spellings where a character may or may not be present. For example, colo#r searches color or colour.

ESCOhost databases use the wildcard symbols above. Other databases may use different symbols. Use the help option in the database or ask a librarian to check on which symbol to use.


Using a truncation symbol allows you to search for alternative word endings.

For example, politic* searches politic, politics, and political at the same time.

The truncation symbol is often the asterisk. However, some databases use other symbols. Use the help option in the database or ask a librarian to check on which symbol to use.

Boolean Operators--Video

A librarian and researcher explore the use of Boolean operators.

Boolean Operators--More Information

See a graphic representation of Boolean operators at The Boolean Machine.

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