An operating system security or access control model where specific types of access to a specific object are granted by giving a process this data structure or token.
The token may be unforgeable (typically by using encryption or hardware "tagged" memory). Capabilities are used in OSes such as Hydra, KeyKOS, EROS, Chorus/Mix, and the Stanford V system. Similar to Kerberos, but in an OS context.
Compare access control list.