Conducting Boolean Searches

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Authors & Contributors

Boolean search allows you to specify the relationships among your keywords and phrases. Boolean search is named after 19^th-century mathematician George Boole, who developed theories for working with sets of information. The most commonly used Boolean search terms include AND, OR, and NOT.

AND Searches: The Boolean search term AND allows you to tell a search engine to locate all records containing one keyword and another. For instance, you could search for all records containing the keywords computers AND writing. This allows you to obtain a smaller number of results than you could by searching for one keyword or the other:

Search for: writing AND computers
Result: all entries containing the two keywords writing and computers

OR Searches: The Boolean search term OR allows you to tell a search engine to locate all records containing one keyword or another. For instance, you could search for all records containing the keywords writing OR computers. This allows you to obtain a larger number of results than you could by searching for one keyword or the other:

Search for: writing OR computers
Result: all entries containing either or both of the keywords writing and computers

NOT Searches: The Boolean search term NOT allows you to tell a search engine to locate all records that do not contain a particular keyword. For instance, you could search for all records containing the keywords composition NOT music. It turns out that the term composition is commonly used in both writing instruction and music instruction. If you are interested in looking only for sources that deal with written composition, you can use the Boolean term NOT to exclude sources dealing with musical composition.

Search for: composition NOT music
Result: all entries containing the keyword composition but not containing the keyword music

Complex Searches: Boolean search terms can be used in combination with each other to construct complex searches. For instance, you could search for all records containing the keywords writing or composition and the keyword computers but not the keyword music:

Search for: writing OR composition AND computers NOT music
Result: all entries containing the keywords writing or composition and computers, but not containing the keyword music