causing the ball to touch the ground or floor outside the opponents' court or without first passing over the net;
catching and throwing the ball;
double hit: two consecutive contacts with the ball made by the same player;
four consecutive contacts with the ball made by the same team;
net foul: touching the net during play;
foot fault: the foot crosses over the boundary line when serving.
The ball is usually played with the hands or arms, but players can legally strike or push (short contact) the ball with any part of the body.
A number of consistent techniques have evolved in volleyball, including spiking and blocking (because these plays are made above the top of the net, the vertical jump is an athletic skill emphasized in the sport) as well as passing, setting, and specialized player positions and offensive and defensive structures.