# Boolean Operators Boolean operators AND, OR, NOT can be applied to searches. Boolean operators must be capitalised, otherwise they are parsed as search terms not as Boolean operators. The symbols &&, ||, !! can also be used instead of the words AND, OR, NOT (please note the symbols must be preceded and followed by a space)

Boolean Operator	Application
AND (also && )	Search for documents containing two or more terms. Each returned search result must contain all of the searched for terms. For example the following queries return search results containing both cat and dog. · cat AND dog · cat && dog
OR (also \|\| )	Search for documents containing at least one of two or more searched terms. For example the following queries return documents containing only the term cat, documents containing only the term dog, and documents containing both cat and dog. · cat OR dog · cat \|\| dog
NOT (also !! )	Search for documents that do not contain a given term. For example the following queries return documents containing cat but not containing dog; · cat NOT dog · cat !! dog

Boolean Operator

Application

AND (also && )

Search for documents containing two or more terms. Each returned search result must contain all of the searched for terms.

For example the following queries return search results containing both cat and dog.

· cat AND dog

· cat && dog

OR (also || )

Search for documents containing at least one of two or more searched terms.

For example the following queries return documents containing only the term cat, documents containing only the term dog, and documents containing both cat and dog.

· cat OR dog

· cat || dog

NOT (also !! )

Search for documents that do not contain a given term.

For example the following queries return documents containing cat but not containing dog;

· cat NOT dog

· cat !! dog

{% hint style="info" %} **Note**: For guidance on using parentheses `( )` with Boolean operators to structure complex searches, see {% endhint %}