Skip to Main Content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.

Advanced Library Research Techniques: Search Operators: AND, OR, NOT

This guide will help you improve your research skills and develop expertise in evaluating, comparing, and selecting reliable and credible sources of information.

Boolean Operator "AND"

Boolean operators consist of AND, OR, NOT, which are used to restrict searches in different ways.

The Boolean operator "AND" is used to join separate search terms together in order to find information that contains both search terms.

For example, if the search terms  "coronavirus treatment" AND  "COVID-19" were to be searched, only results containing both search terms will appear.

Note that the quote marks around a search term ensure that the results found must contain the word(s) or phrase exactly as it appears inside the quotes.

"coronavirus treatment" AND COVID-19

Boolean Operator "OR"

The Boolean operator "OR" is used between two separate search terms in order to find any information on either search term.

For, example, if the search term "coronavirus treatment" OR the search term "COVID-19"  were to be searched, all results containing either search term will appear. Search results containing both terms would also of course be included in the mix.

"coronavirus treatment" OR COVID-19 treatment

Site Searches

Google Advanced Search Shortcuts

Use these two sites if you want authoritative information*

Government Website Searches:

Educational Sites Searches:

PowerPoint Sites Searches:   transgender: .ppt

Military Sites Searches: transgender: .mil

*After your keyword (transgender) add a colon (:) and a domain (.gov .edu, .ppt .mil etc.), with no space between the colon and domain.




Boolean Operator "NOT"

The Boolean operator "NOT" is used to specify which search term you want to exclude from the information you are searching.

For example, if the search terms "coronavirus treatment" NOT "Virginia" were to be searched, only "coronavirus treatment" results not containing "Virginia" will appear.

"coronavirus treatment" NOT Virginia


You can add special symbols called "wildcards" (* or ?) to a search term in order to receive more results.

Often times this is used if a you're not familiar with a spelling, a word has multiple spellings, or you're trying to recall specific information.

Different search tools, databases, and database providers utilize different wildcard characters.

One or No Character Wildcard Searches

Some database providers such as Gale, have an option to search one or no unknown characters.

Gale - One or No Characters

For example, the search above will result in all occurrences of "flavour" or "flavor".

This means that the wildcard character either represents a letter or no letter at all.