Boolean Operators and Modifiers

Once you've chosen your search terms, you're ready to combine them to create your search strategy.

Terms are combined using Boolean operators. They are a set of commands that search engines, online catalogues, and databases are able to understand. They also make searching more efficient by letting you combine dozens of queries into one search. Boolean operators include AND, OR, NOT

Another set of commands, called Boolean modifiers, allow you to instruct the database to group your terms (parentheses) and search for variant word endings (truncation) and exact phrases.

Need more help? See our page on Boolean operators. 

Narrow Your Search: AND, NOT

AND tells the search engine to only return results that contain all the words you've entered. Since the search is more specific and selective, you'll retrieve fewer results.

Example: disability AND faculty AND attitude

NOT tells the search engine to give you results that contain all of the words you entered except the word following NOT.

Example: Tudor NOT Victorian

Expand Your Search: OR, Truncation

OR tells the search engine to give your results that contain any of the terms you've entered. This creates a broader search, so you'll retrieve a greater number of results.

Example: faculty OR professor OR instructor

Truncation (usually represented by an asterisk *) allows you to search for multiple endings of the same root word.

Example: Elizabeth*

Phrase Searching

Search for two or more words as a unit by putting them in quotation marks. This is especially useful for titles or phrases.

Example: "Queen of Scots"

Combining Searches

By using parentheses, you can ask a search engine to perform several Boolean searches at the same time. The search engine will perform the search enclosed in parentheses first, before moving on to the other search terms.

Example: (Elizabeth I OR Elizabeth Tudor) and (Spanish Armada OR Spain OR Spanish Invasion) and (Image OR Identity OR Portrait)

*Created by McMaster Libraries