“Comp” is short for complimentary. They're the nice perks that casinos give you just for playing. Depending upon your betting level and how long you play, you could get comped to a buffet, a cafe, a gourmet room, a hotel room, a suite, even air fare. And by playing blackjack you can get the most in comps compared to other casino games. There are several ways in order to achieve this.
First let's make sure you understand how casinos determine how much your action is worth. Action is defined as the amount of money you risk over time. Assuming you are dealt 100 hands per hour, your average bet is $10, and you play for 4 hours, your total action is 100 hands x $10 per hand x 4 hours = $4000. In your 4 hours of play you've given the casino $4000 worth of action. Casinos use the following formula to calculate how much of a player's action they expect to win:
Action x Casino Advantage = Player's Theoretical Loss
Since pit bosses can't watch the play of every individual blackjack player to determine their skill level, they will generally estimate a 2% advantage over the masses of players that play blackjack. This means they expect to win about $80 in the above example ($4000 x 2%). Most casinos will give players comps worth 20 to 40% of a player's expected loss. This means the above player can expect a comp worth about $25.
Now here is how a blackjack player can get more in comps then their theoretical loss. First a player can and should learn the basic playing strategy. This is a set of rules that tells the player when to hit, stand, double down, pair split, and surrender. By learning and using the basic strategy flawlessly at the tables, a player will reduce the casino's edge from 2% (which is what the pit boss is estimating) down to 0.5%. Now let's recalculate the player's expected loss in the above example. With a 0.5% casino edge facing the player his expected loss is only $20 ($4000 x 0.5%). Your expected loss is only 25% of what the casino thinks they are going to win from you.
Do you see where this is heading? The pit boss has the player earmarked for a $80 theoretical loss so he dolls out a comp worth $25. Meantime the player's actual expected loss is only $20. The player is actually ahead of the game by $5. Not a bad deal. If you think this is a good, wait to you see how you make it even better. Instead of playing 100 hands per hour, S-L-O-W down your play at the tables. You can do this by playing at full tables instead of tables with only a few players. Take your time making your playing decisions. Skip a few hands and take a few "restroom" breaks. The point is that if you slow down your play so that you are betting on only 50 hands per hour (instead of 100) your expected loss drops to $10 and you are still getting $25 worth of comps. Now you're ahead by $15 instead of $5.