A capability is a set of access rights granted to a subject, often transferable. Capabilities are a method for access control.
Capabilities are tokens that represent a set of access rights given to a principal in a system. The possession of a capability indicates that the principal has is authorized to make the access that the capability indicates. An example of a capability is “this process may access the file F”.
A dual approach to capabilities is access control lists, where the object contains the list of principals that may access it.
See also access-control.