Polkit, or Policy Kit, handles the policies that let unprivileged processes talk to privileged ones via D-Bus APIs. For example, not all programs should be allowed to request that the machine be disconnected from the network via the NetworkManager service.

Polkit lets the system administrator define different policies for different services. For example, only a user with physical access to the console may mount/unmount drives and volumes; users that are not at the console will need to type an administrator password. On a machine for home users, most policies will be rather liberal, as the users can be trusted to take care of the machine. On corporate settings, policies may be more restricted.

GNOME uses PolicyKit whenever applications need to request privileged operations.