When playing person-to-person defense, the defender must always react to the offensive player. If everyone is able to keep up with his/her check, this works well. However, playing a zone defense forces the offense to react to the specific defensive set up. Here is a listing of several different zone defenses.
Perhaps the most important thing with a zone defense is good communication. Each line of the zone defense will talk to the previous line letting them know who is behind them. (e.g. The deep(s) will talk to the middles.) The players who are not playing can also help a great deal with communication.
(Note: the left middle and right middle are also called the left hammer or left hammer stopper and the right hammer or right hammer stopper.)