Discretionary Access Control (DAC) defines basic access control policies to objects in a filesystem. In security, specifically location security, the term access control refers first to the practice of restricting entrance to a facility or property to authorized persons, and secondly to the mechanisms which keep track of entries and exits (i. ... See Filing system for this term as it is used in libraries and offices In computing, a file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. ...

Generally, these are done at the discretion of the object owner -- file/directory permissions and user/group ownership.

The Telecom Glossary defines DAC as "A means of restricting access to objects based on the identity and need-to-know of users and/or groups to which the object belongs. Controls are discretionary in the sense that a subject with a certain access permission is capable of passing that permission (directly or indirectly) to any other subject."