> A capability is like a $5 bill.... a stand alone one time access to resources. It's rather not like this. A capability references the resource(s) that it giv

> A capability is like a $5 bill.... a stand alone one time access to resources. It's rather not like this. A capability references the resource(s) that it gives access to. Better off with an excerpt from Wikipedia: > A capability (known in some systems as a key) is a communicable, unforgeable token of authority. It refers to a value that references an object along with an associated set of access rights. A user program on a capability-based operating system must use a capability to access an object. The catch phrase I keep in my head is "possession is ability" and similarly ability requires a capability (token). The capability names the resources, the actions, etc. The system does not have to look up the token somewhere to see what the authorizations cover, it's in the capability itself. There is some detail in sharing between processes, e.g. the capability being shared has the capability to share it, and use of a mechanism that maintains integrity.