FAQ: What is Boolean searching and how can I use it in library databases?

Boolean searching is used to help find search results faster and with more precision. Boolean searching uses operators: words like AND, OR, and NOT. These are logic-based words that help search engines narrow down or broaden search results.

Using the Operators

AND

The Boolean operator AND tells a search engine that you want to find information about two (or more) search terms. For example, cats and dogs. This will narrow down your search results because the search engine will only bring back results that include both search terms.

OR

The Boolean operator OR tells the search engine that you want to find information about either search term you've entered. For example, cats or felines. This will broaden your search results because the search engine will bring back any results that have either search term in them.

NOT

The Boolean operator NOT tells the search engine that you want to find information about the first search term, but nothing about the second. For example, cats not dogs. This will narrow down your research results because the search engine will bring back only resources about the first search term (cats), but exclude any resources that include the second search term (dogs).

Uses

Most Useful For

• Narrowing down or broadening your search results by connecting search terms together using logic
• Making connections between keywords or emphasizing relationships between keywords when searching

Cautions

• May bring back too many, too few, or irrelevant results if keywords are not carefully selected
• Not all databases handle Boolean operators in the same way (e.g. some support nesting, some databases support symbols like "&", etc.)