The Offside
A player is in an offside position if he is nearer to his opponent’s goal line than both the ball and the second last opponent. A player receiving the ball directly from a goal kick, throw in or corner can’t be offside.
Examples
This is offside because the red number 10 attacker is in front of all of the defenders, leaving only the goalkeeper back – which isn’t enough players to play red 10 onside. This position may have been forced by the defenders moving forward in what is called ‘the offside trap’
Here we can see that the blue number three defender has failed to move up the field with rest of his defence, and so has played the red number nine attacker onside. This is a classic example of where the offside trap fails.