Permissions (or privileges) control access to content.

Granularity? refers to how fine permissions can be divided.

Permissions can be per user, or based on their Role. They can be given to a Group of users, then users assigned to the group. It can be per page or even per Content Element. It can depend on the time. For example, a user may edit a page scheduled for a future date, but not change it once it is published.