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Effective Search Strategies: Boolean Operators

How to search effectively using keywords, boolean operators and other options.

Boolean Operators

Keyword searches work with three basic operators, involving Boolean logic. Boolean operators tell the computer whether you want to:

  • find all the words (AND)
  • find any of the words (OR)
  • exclude a word (NOT)

Today, most databases automatically search for all the keywords you typed (AND), because it's the most common and useful way to narrow a search.

But you may find some advanced search forms will display a choice of operators, so that you can see them work, such as in the JEWL Search advanced search.

AND
 Searching elections AND contributors will find resources with both terms, giving you more specific results. 

OR
Searching political action committee OR pac; college OR university, corn OR maize using the OR operator will find resources with either term or both, giving more results.

NOT
Searching elections NOT presidential will find resources on elections (local, Senate, etc.) but exclude information about presidential elections.

Caution: Be careful when using NOT! The term you want may be present in an important way in results that also contain the word you wish to avoid.

Truncation

A truncation symbol allows you to search for alternative word endings.

Example: politic* searches politicpolitics, politicians 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.

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*

Note: Some databases create the combining for you when using an advanced search box, such as in JEWL Search.

Phrase Searching

If you enter a search such as grade inflation without any Boolean operators, some databases will search for the terms separately. Others will search for the phrase. To guarantee you search for the phrase--the words together in the specified order--use quotation marks.

"grade inflation"

Credit: This page is adapted from South Dakota State University.

Boolean Operators - More Information

The Boolean Machine is a website with a graphic representation of  AND, OR, NOT. Hover over each operator to see how it works.