Boolean Searching refers to how multiple terms are combined in a search.

and requires that both terms be found.
or lets either term be found
not means any record containing the second term will be excluded
( ) means the Boolean operators can be nested using parentheses
+ is equivalent to AND, requiring the term; the + should be placed directly in front of the search term
- is equivalent to NOT and means to exclude the term; the - should be placed directly in front of the search term

Operators can be entered in the case shown by the example.

Examples:
(salad and (lime or kiwi)) not nuts
+salad -nuts lime kiwi