Comp – complimentary items that are provided by casino for free as regular promotions. For example, this could be free drinks, meals, money bonuses, tickets to different casino shows, tournament entries, private gaming rooms, transport service, etc.
Most big casinos offer their players the so-called "RFB" package which includes "room, food, and beverage" and smaller bettors can benefit from "RF" casino package (room and food).