Boolean operators are words and symbols, such as AND or NOT, that let you expand or narrow your search parameters when using a database or search engine. When you search using these operators, it is known as a Boolean search.
You can use Boolean operators such as AND, OR, and NOT alongside keywords to create a Boolean string that will refine your search to find the most relevant results and sources.
Knowing how to use Boolean operators effectively can save you a lot of time and help you to find useful sources, determine the relevance of your research topic, and create strong research questions.
| Boolean Operator | Function | Example |
|---|---|---|
| AND | Provides results that contain both or all keywords | paradigm AND syntagm |
| OR | Provides results that contain either keyword | meteor OR meteorite |
| NOT or AND NOT | Provides results that contain the first keyword but not the second | football NOT soccer |
| Quotation marks "" | Provides results with the exact phrase | "Newtonian mechanics" |
| Parentheses () | Allows you to group together keywords and control the order in which the terms will be searched | (rural OR urban) AND sociology |
| Asterisk * | Provides results that contain a variation of the keyword |
Develop* This will return results containing words such as "development," "developer," and "developing." |
Check out Scribbr for more information
If you're having trouble coming up with keywords for your search, take a look at subject headings. If you find one article that looks relevant to your topic, scroll down to the metadata for the article. You should find a set of subject headings that look something like the image below.
These are the subjects covered in the article you're looking at. You can click on these links to open other articles related to those topics.
