A field goal is an open-play goal that can only be scored from inside the "striking circle," in front of the opposing goal. A goal is not scored if the hockey ball is struck from outside the circle and enters the goal. Hockey players are not permitted to trip, shove, charge, interfere, or violently handle an opponent in any way. They may not use their hands as a weapon unless they are wearing gloves. Field goals can also be scored by taking a penalty stroke. A player who has been penalized for holding the stick too long can score a penalty shot by releasing the stick and hitting the ball with either foot. The shooter must take the penalty stroke from directly behind the center of the goal or else it is invalid. If the player scores, the release was valid and the goal will count. There is one exception to this rule: if the player being penalized is injured while taking the penalty shot, another player can take the shot in his place. The original player is given a free kick instead. The only other way to score is with an own goal. This happens when a player allows the ball to go into his/her own net by accident or misunderstanding the direction of the play. It can also happen if a player tries to pass the ball but misses and it goes into his/her own net. An own goal cannot be scored with the foot; instead, it has to be released with the head or chest.