Coffee beans naturally contain caffeine. At the store or in a restaurant, you can choose "decaffeinated coffee".
Is really all the caffeine gone or is there just a smaller amount? How do they remove the caffeine from the beans?
The most commonly used method is the Swiss Water Process:
There's no universal definition of "Decaf," but it generally means beans that have had at least 97% of the caffeine (by weight) removed.