Discretionary Access Control (DAC): A type of access control where the owner or administrator of the protected system, data, or resource sets the policies defining who or what is authorized to access the resource. In DAC models, access is based on the discretion of the owner. Users can be granted permission by an owner to read, write, or execute a file or program. This model is contrasted with mandatory access control (MAC), where access rights are regulated by a central authority based on multiple levels of security. DAC is known for its flexibility but can be less secure than MAC, as it allows users to control access to their own data, which they may not always do securely. DAC can lead to security risks if users are not careful in managing permissions.