Chapter 8: Gathering Research and Establishing Evidence

Boolean Operators

Databases and search engines use Boolean logic. Named after mathematician George Boole (1815-1864), Boolean logic is the key to successful database searching. By using the Boolean operators AND, OR, and NOT (sometimes expressed as ANDNOT) between search words, a researcher can focus or broaden a search query to create sets of results. The operators are normally expressed in uppercase letters so as not to confuse them with the words used as non-operators.

When you see a simple search box and type in words, the search engine generally inserts the AND operator between every word. By using an advanced search option, you are encouraged to think about the way you want to focus your search.

Watch Video 8.3 to learn more.