What does "rake back" mean?

A. Rake back is the type of bonus when player can:

- get back a part of his own rake previously paid to a poker room;

- get back a part of referred users' (or affiliated users) rake (the best affiliated system offering rake back is in Poker Champs).

Rake back can be given by some websites as a kind of bonus, but usually it is the incentive of website staff, not poker room.