The holder kneels down and sets the hand furthest away from the line of scrimmage on the ground, holding out the other hand, waiting for the ball to be snapped to him. After receiving the ball, the bearer rapidly sets it on the ground, with one end touching the ground and the other maintained by one finger. He then rises up onto his knees and arms in order to protect the ball while he is being pursued by opposing players. At the end of each period of play, the referee blows the whistle and awards the ball to either team without specifically naming who is holding it. This is called "giving away the ball." The team that has the ball may not touch it with their hands unless they are in their own territory, at which time they can put it through their own end zone for a touchdown or into the opposition's end zone for a field goal. In addition to the referee, two other officials are on the field at all times during a game: a linesman, who is responsible for ruling on whether a player is offside; and a back judge, who watches for illegal contact behind the line of scrimmage. These officials can also change directions quickly, making them effective defenders against counterattacks and screen plays. By the 1920s, most teams had adopted the custom of having a specific person assigned the duty of holder. This person would take care of both the kicking game as well as handing off the ball.