The main types of defensive strategy in basketball are the so-called zone and man-to-man defenses. In the zone defense, each player is responsible for defending a certain area of the court around the basket at which the opposing team is shooting. In a man-to-man, or one-on-one defense, each player is assigned to guard closely a specific member of the opposing team. Zone defense is not permitted in professional basketball, but remains an important part of amateur competition. Individual defensive skills include the ability to block shots without fouling, to break up passes, and to steal the ball. A change-of-hands of the ball in floor play, from one team to the other, is called a turnover. Intense or pressing defensive moves include double-teaming, whereby two players guard a dangerous or vulnerable opponent, and the full-court press, in which the team with the ball is aggressively challenged the whole length of the court. A skill vital to both defense and offense is rebounding—the ability to wrest possession of the ball under the opponent's basket.