What are volleyball fouls?

There are two main ones. During your service if you step on or over the line then a foul is called. Also,if you don't release the ball 5 seconds after the ref's whistle to begin the service you are called a foul. When the foul is called for both of these errors, the other team gains possession of the ball. Also there is another more complicated rule. If you throw the ball in the air and realize it is a bad toss you don't want to hit then you are allowed to let the ball hit the ground, but only ONCE per that rotation of serves. The next time that you come around the court to serve, you may drop it only once again. Another foul called is when you serve before the ref's whistle. Depending on the ref, you will either get a second chance or the other team gains possession of the ball.