What is an access control list (ACL)?

The Microsoft Windows 2000 Active Directory glossary defines an access control list as “a set of data associated with a file, directory, or other resource that defines the permissions that users and/or groups have for accessing it. In the Active Directory™ service, an ACL is a list of access control entries (ACEs) stored with the object it protects. In the Windows NT® operating system, an ACL is stored as a binary value, called a security descriptor.”