Boolean Logic Research Guide
Reference Desk (413) 774-1509	Research Guides | Library Home

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In order to keyword search efficiently in any library catalog, research database, or on the Internet it is necessary to understand Boolean Logic.

• Boolean Logic involves connecting major concepts with Boolean operators to construct a search strategy that results in useful and relevant results.
• The Boolean Operators are AND, OR, and NOT.
• DO NOT search catalogs and research databases using long phrases or full sentences
• Combine major concepts and/or short, common phrases (child development, civil rights) with Boolean Operators

What about the Internet?

• Google and other search engines use Boolean Logic
• When searching Google, the operator AND is assumed between all of the words typed into the search window--" " must be used to search for phrases
• In the Advanced Search, there are options for searching ALL of the words (AND) or ANY of the words (OR)
• Some databases assume that two words strung together are a phrase while others, just like Google, require that " " be placed around phrases

Remember:

• READ THE HELP SCREENS FOR THE DATABASE TO LEARN NOW TO SEARCH EFFICIENTLY
• Do not wade through thousands of results in a catalog or database--this is a waste of valuable time
• Ask a Librarian for help with searching efficiently or call the Reference Desk at 774-1509

	AND narrows the search to require that BOTH concepts are present in the results. In other words, when concepts are connected with AND, all of the concepts must be present in the results. children AND television television AND violence
	OR broadens the search to include either concept. When concepts are connected with OR, any of the concepts can be present in the results. OR is often used to search for synonyms or variant spellings. greenhouse effect OR ozone OR can also be used in a more complex search to locate several pieces of information about a given topic. When using AND and OR in a search, the words connected with OR must be surrounded with ( ) in order for the search to work correctly. This is called "nesting". civil rights and (prejudice or segregation or violence)
	NOT excludes words from the search to narrow the results. It should be used seldom and very cautiously. Caribbean NOT Cuba drugs NOT steroids

For additional searching tips see:

• Keyword Search Concepts (includes nesting & truncation)
• Searching Skills: terminology and concepts, the search process