Privileges, Roles, and Users
Roles contain privileges and users. Users have privileges based on their membership in roles. If a user is a member of a role, the user has the role's privileges. A role can contain multiple users and a user can be a member of multiple roles.
Roles can also contain other roles. If role A contains role B, then a user who is a member of role B has the privileges of both role A and role B. A user who is only a member of role A has role A's privileges but not role B's privileges.