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Library Instruction: Boolean Operators

Boolean AND

AND locates records containing both terms. For example, a subject search on "diet AND cancer" locates records that contain information on both diet and cancer as indicated by the overlapping yellow area below. Boolean AND

Boolean OR

OR locates records matching any or all of the specified terms. For example, a search on "diet OR nutrition" locates records that contain information only about diet, records only about nutrition, and records that contain information on both diet and nutrition. OR expands your search. Boolean OR

Boolean NOT

NOT locates records containing the first term but NOT the second. For example, a search on "cancer NOT diet" locates records only about cancer, and excludes any records about diet that also contain information about cancer. Photobucket

Boolean Operators

Boolean Operators help to focus your search by linking your search terms. There are three words that are used as Boolean connectors, ANDOR and NOT

The diagrams on this page help to explain further how Boolean Operators work. 

Boolean Operator Examples

Boolean Operator




children AND poverty

diet AND cancer 

AND combines different terms when both must be present. Use AND to narrow a search.


children OR youth

    cats OR dogs 

Generation X OR Generation Y 

OR combines either synonymous terms when at least one must be present. 

OR also locates records that contain information on all the terms selected. 

Use OR to broaden a search.


juvenile NOT crime

Richard Nixon NOT Watergate 

Men NOT women 

NOT eliminates irrelevant terms from a search. Use NOT when you want to exclude all records that contain a term.

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