Legal guarding involves a defender placing their body in front of an offensive opponent. To be in a legal guarding position, the defender must have both feet on the floor facing the opponent. The principle of verticality applies, where the defender must remain in their vertical plane and not extend their arms, shoulders, hips or legs outside of it. A blocking foul occurs when a defender makes illegal contact that impedes an opponent through an illegal guarding position. A player control foul happens when an offensive player makes illegal contact with a legally guarding defender, requiring them to avoid contact by stopping or changing direction.