After an identity is suitably authenticated, the natural next step is to use that identity to authorize access to a resource. Windows has a very expressive authorization model available for applications and system components to use for making authorization decisions.
Windows was originally designed to meet the requirements of the C2 level of the Trusted Computer System Evaluation Criteria (TCSEC). The TCSEC program has since been supplanted by profiles written under the Common Criteria for Information Technology Security Evaluation, such as the Controlled Access Protection Profile. These profiles and related information can be found in section 6.
The C2 requirements (and later the CAPP requirements) for authorization are centered on discretionary access control. For discretionary access control, the owner of a particular resource (or a delegate of the owner) determines what access others should have. This is in contrast to mandatory access control schemes in which another party maintains control over the resource regardless of the expectations of the owner.