Why use Boolean operators?
To focus a search, particularly when your topic contains multiple search terms
To connect various pieces of information to find exactly what you're looking for
AND |
Use this word between concepts to narrow your results. |
e.g. sensory AND perception |
OR |
Use this word between related concepts. |
e.g. habitat OR ecosystem |
NOT |
Use this word to exclude terms from your search. |
e.g. virus NOT corona |
Quotations |
Use quotes to search for a multi-word concept. |
e.g. "International Year of Indigenous Languages" |
* |
Use the asterisk symbol to include alternate word endings. |
e.g. cultur* will search for culture, cultural, and culturally |
? |
Use a question mark to include variations in spelling in your search. |
e.g. wom?n will search for woman, women |
( ) |
Use brackets to create separate groups of actions in your search. |
e.g. "climate change" AND (ecosystem* OR habitat*) AND Ontario |
Use AND in a search to:
- narrow your results
- tell the database that ALL search terms must be present in the resulting records
- example: cloning AND humans AND ethics
The red triangle in the middle of the Venn diagram below represents the result set for this search. Joining all three terms with AND will produce a smaller result set.

Use OR in a search to:
- connect two or more similar concepts (synonyms)
- broaden your results, telling the database that ANY of your search terms can be present in the resulting records
- example: cloning OR genetics OR reproduction
All three circles represent the result set for this search. It is a big set because any of those words are valid using the OR operator.

Use NOT in a search to:
- exclude words from your search
- narrow your search, telling the database to ignore concepts that may be implied by your search terms
- example: cloning NOT sheep