Boolean is a set of commands that can be used in almost every search engine, database, or online catalogue. The most popular Boolean commands are AND, OR, and NOT. Other commands include parentheses, truncation, and phrases.
Narrow your search using AND
Using the Boolean command AND in your search tells the search engine to give you results that contain all of the words you have entered.
media AND violence: only those results that contain both media and violence will appear in your search results list.
Expand your search using OR
Using Boolean command OR in your search tells the search engine to give you results that contain any of the words you have entered.
teenagers OR adolescents: any results that contain either teenagers or adolescents will appear in your results list.
Narrow your results using NOT
Using Boolean command NOT in your search tells the search engine to give you results that contain the word(s) you entered except the word following NOT.
Psychology NOT Developmental: any results that contain the word "psychology" will appear in your results list except those results that also contain the word "developmental".
Capitalize your Boolean commands. Some databases only accept these operators when they are capitalized.