In the context of casinos, comps are complimentary items and services given out by casinos to encourage players to gamble. The amount and quality of comps that a player is given usually depends on a combination of factors: what game(s) they play, how much they bet, and how long they play.
Most casinos have casino hosts who are responsible for giving out free items and contacting players to bring them back to the casino. Pit bosses can also award comps at table games. Most casinos now urge players to obtain a player's club or similar card, so that their play can be tracked and comps awarded.
The second level of comp that many players earn is free self-parking, lounge access, or free meals. Many casinos have several players lounges and restaurants, and may require more play to earn a comp to higher-end restaurants. Often the player is given a certain amount to spend, but sometimes, particularly with high rollers, the player may be given the right to order as much food as they want and to bring guests.
The next level of comps is usually free hotel rooms, free valet parking, and free access to more exclusive VIP or "high roller" lounges. Many casinos have attached hotels, but those that do not may have the ability to comp rooms to a hotel nearby. Many casino hotels have higher quality rooms, such as suites, villas, presidential suites, and so on for bigger bettors or VIP guests. Many players who receive hotel rooms receive a package called "RFB" (for "room, food, and beverage") or "RF" (for "room and food") for smaller bettors, or in jurisdictions where casinos are not allowed to give free alcohol.
Many casinos also offer other comps, especially to high rollers. These may include airfare reimbursement, limo rides, tickets to shows, golf, free concierge services, cash back, money to show up in the casino, loss rebates, private gaming areas, and private jet service.
Casinos also frequently offer players comps by mail or email, or in casino apps. These may be free bet offers, free meals, discounted or free rooms, or entries into tournaments or prize drawings.
Some casinos contract with bus companies to bring players in. Riders often enjoy free slot play, dining coupons, and other benefits, often worth as much as the bus fare itself.
Technically, every player may be offered comps, but most casinos require players to have played for a given period of time and play at a certain level, i.e., the duration of play and amount wagered are directly proportional to the level of expected comps. What games are played are also factors. Casinos award comps based on a player's Average Daily Theoretical loss, also known as ADT, theoretical loss, or "theo" for short. The theoretical loss is the amount of money a player is expected to lose based on the long run statistical advantage the casino has on the particular game being played.
- Theoretical Loss = (Casino Advantage) × (Total Wager)
Players known as "comp counters", "comp hustlers", or "comp wizards" attempt to maximize the amount of comps they receive while minimizing their expected gambling losses. Comp hustlers play games with a low house advantage, such as blackjack or video poker, or games with small bet sizes, such as penny slots. Comp hustlers may use tactics such as placing large bets when a pit boss is checking their bet size to rate them for comps, and then moving to a smaller bet size when the boss is not watching. They may also take frequent breaks from playing, play at full tables to be dealt fewer hands per hour, and play more slowly. Comp hustling is a type of advantage gambling if the player is able to hustle more in comps than their average cost of gambling. And the author of "How to Get a Dollar in Casino Comps for Every Dime You Lose Gambling", in their summary of key takeaways from Max Rubin's book, Comp City, observes: "The next step up from being a comp wizard is to become a comp counter. These players have specific knowledge and skills that enable them to combine a low house edge with comps in order to profit." Another step up are practitioners of "ACES (Advanced Comp Earning System). People practicing this kind of system earn a dollar's worth of comps for every dime they lose gambling."
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Online casinos, poker rooms, and sportsbooks offer a variety of bonuses that are similar to brick and mortar casino comps. Also similarly, comp hustlers and advantage players can use these bonuses to turn a profit via bonus hunting, or can convert these comps to a guaranteed profit using the technique of matched betting.
Many online casino operators are aware of the potential for losing money while giving out bonuses. As such, there is often a minimum wagering requirement for cashing out.
Some casinos will limit the payout in case of a win. Also, they may restrict players from playing certain games, often those games with a low house advantage. And, they may require players to bet the bonus amount multiple times before being able to cash out. For example, a casino may require a player to bet the bonus amount 50 times before being able to cash out. So, for a $100 bonus, a player would have to bet $5,000 before being able to cash out. Therefore, it is advantageous for players to check the wagering requirements of a bonus. All bonuses have a turnover requirement. This means that placing a certain number of wagers, such as turnover 5x, means wagering 5 times the bonus. Most online casinos distinguish two types of bonuses: a no deposit bonus and a deposit bonus. First one does not require from a user to make a deposit at a casino in order to start playing. A deposit bonus requires from a user to make a deposit of certain amount of funds to start playing at the casino. Both of these type bonuses apply to terms and conditions of turnover requirements. 
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