A zone defense in basketball is a defensive formation strategy where players are assigned specific areas or zones on the court to protect. If an offensive player enters the defensive player's assigned zone, he must guard against him.
This is different from the more traditional defensive strategy of man-to-man defense, in which each defensive player guards matches up to guard an offensive player. To learn more about man-to-man defense, visit the Basketball Man to Man tutorial.
The 1-3-1 is one of the more common zone defenses. It is designed to prevent the ball from getting to the painted area, but it can suffer greatly against solid perimeter shooting from the wing or corner areas.
The 2-3 zone is easily the most common zone defense. It is easy to explain, execute, and exploit. The strength of the 2-3 zone is its ability to defend against drives, but its weaknesses lie in guarding perimeter shooting and the center of the floor.