Chips and comps
In most American casinos, a black chip is worth $100, a green chip is worth $25, and a red chip is worth $5.
"Comps" are free, or "complimentary" gifts given to you by the casino. They range from free drinks to meals to hotel rooms and can even include things like air fare or Super Bowl tickets. It all depends on your level of play, the amount of time you spend gambling in the casino, and the specific casino in which you are playing. Someone who is playing "red," that is, playing with betting levels of $5 to $25 is going to get free drinks and perhaps a reduced room rate, but not much else. A green player who bets $25 to $100 might get a few free meals and may even be able to get a free room in some places, but he's not going to get what is called "RFB," which means a full "room, food and beverage" comp in most Strip casinos, although he might do quite well downtown or in locals casinos. A player whose average bets are $100 or more will qualify for an RFB comp in most Las Vegas casinos, but the poshest places, like Bellagio, will want an even higher betting level for an RFB comp. The really exclusive comps are reserved for the high rolling players who are betting hundreds or even thousands of dollars per hand.
A table player can get comps by asking to be rated each time he plays and then asking the casino host for comps. Once you become a rated player you can also get comps through the mail for a variety of special offers. Often, the comps obtained through the mail are better than you might get for your play from a casino host.
There is a lot more to this than I just described. Comp City is a book that gives a lot of hints on how to get comps, and Jean Scott's book, Frugal Gambler is an excellent guide for a low-roller wanting to get comps.