System privileges are granted to users, groups, and roles to give them the right to perform particular types of action in the database. By default, a user belonging to a group or having a role inherits the group or role privileges and these inherited privileges are identifies as such in the Privileges tab of the user property sheet. A user with an administrative profile is also allowed to revoke a privilege.
System privileges are used in association with object permissions (see Granting Object Permissions) to evaluate the rights of a user, group, or role. For example, even if a user has the Modify privilege, he cannot modify an object on which he has no Update permission.