Using Boolean Operators with parentheses
To make even better use of Boolean operators, you can use parentheses to nest query terms within other query terms.
You can enclose search terms and their operators in parentheses to specify the order in which they are interpreted. Information within parentheses is read first, then information outside parentheses is read next. For example,
When you enter
(Ambrosia OR ragweed) AND allergies
the search engine retrieves results containing the word Ambrosia or the word ragweed together with the word allergies in the fields searched by default.
Boolean without parentheses
If the Boolean queries do not include parentheses,
Ambrosia OR ragweed AND allergies,
the search engine will follow an order of operations like in math where AND is considered multiplication and are processed first, followed by the OR clause which is addition. Effectively, the search engine processes Ambrosia OR ragweed AND allergies as though the query has parentheses in the following place:
Ambrosia OR (Ragweed AND allergies)
Note: When executing a search, And takes precedence over Or.