The casino host has the power to issue complimentary services (or "comps") to players.
Comps can range from complimentary meals, beverages, and show (concert or theater) tickets right up to full accommodation in a hotel casino.
Comps issued by hosts vary greatly and can be anything from a free buffet coupon, overnight hotel accommodation and upgrade, or entertainment tickets, to luxurious villas and private charter flights to the casino.
The level and issuance of these comps by the host is done using mathematical formulas that calculate a player's theoretical loss (also known as "ADT" for average daily theoretical, or "theo"), based on wager size, session length, and the house edge of the game.
Based on this formula, the host will be authorized to re-invest a percentage of the house's theoretical win back into the player by issuing freebies with the aim of building a loyal relationship with the player.