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 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 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. 
Boolean Operators
Boolean Operators help to focus your search by linking your search terms. There are three words that are used as Boolean connectors, AND, OR and NOT.
The diagrams on this page help to explain further how Boolean Operators work.
Boolean Operator Examples
|
Boolean Operator |
Examples |
Retrieves |
|
AND |
children AND poverty diet AND cancer |
AND combines different terms when both must be present. Use AND to narrow a search. |
|
OR |
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. |
|
NOT |
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. |