How do you know if a soccer player is offside?

Answer 1

There are two parts of the offside rule (Law 11 of the Laws of the Game): the position and the infraction. Specifically, a player in an offside position is not necessarily automatically guilty of the offside infraction.

A player is in an offside position if, at the time the ball was last played by a teammate, he (or she) is nearer to the opponent's goal line than the ball and the second-last opponent (including the goalkeeper), and is not in his own half of the field (all it takes is a toe touching the halfway line to be "in his own half"). A player is not "nearer to the opponent's goal line" than any defender with whom he is even or level. Also, the goal line stretches from corner flag to corner flag, not just the mouth of the goal.

It is not an infraction to be in an offside position. It becomes an infraction if and only if the player becomes involved in play by playing the ball, interfering with an opponent (such as by chasing the ball or blocking the goalkeeper's view of the play), or gaining an advantage by being in that position (such as playing a rebound from the goalpost).

If a player is in an offside position AND becomes involved in the play as described above, he is guilty of the offside infraction.