The Boolean AND is implied when multiple terms are entered. For example, user role returns a results list of pages that contain the string user and the string role.
Use quotes to search for an exact phrase instead. For example, "user role" returns a list of pages that contain the exact expression user role.
The Boolean OR returns hits for pages that contain either term. For example, "user role" or "role requirements" returns pages that contain either of those phrases.
The Boolean NOT operator returns hits for pages that contain one term but do not contain the term that follows the operator. For example, role not requirements returns pages that contain role but not requirements.
You can use parentheses to construct compound Boolean expressions. For example, admin AND (requirements or role) returns pages that contain both admin and requirements or admin and role.