There are two sorts of rule breaches to avoid in volleyball: playing violations and technical violations. First, there are the rules infractions. Playing offenses include hitting the ball into or under the net, outside the antennae, and beyond the bounds of the opponent's court. Hitting the ball twice in the same act is also a violation. Defenders are allowed to hit with any part of their body except their hands and arms; therefore, all offensive actions should be anticipated by the defender first. For example, if the attacker throws the ball at him, the defender can hit it away even though he didn't see it until after it was thrown. The other type of offense is the technical one. This includes serving with both feet off the floor, holding the ball too long, and faking an injury. These are all serious violations that may result in sanctions including penalties points, time-outs, and disqualifications. Finally, there are three types of defensive techniques: blocking, tackling, and screening. Blocking is used to stop a shot by jumping with your legs and arms. You can block either offensively or defensively. Tackling is similar to blocking in that you use your body to stop a ball carrier. However, instead of jumping, you reach out and try to catch the player by the arm or leg. Screening is used when you want to block a pass by jumping but the ball is high enough that it won't hit you.