REFEREE MECHANICS
During your pre-game instructions, be very clear on the way you and your partner will handle offside. Normally, a slow and correct call is much preferred from a fast and incorrect call. Remember to judge involvement of the player before making the decision to call an offside. Remember when to not call an offside. For example, if the ball rolls directly to the keeper who can punt the ball away much more effectively than having to perform an indirect free kick. During the game, make sure to position yourself to keep even with the second-to-last defender.

THE IMPORTANCE OF PROPER POSITIONING
The proper mechanic for a referee is to line up with the second-to-last defender so that they can accurately determine if the attacker is involved in the play and nearer the goal line than the defender or the ball. The picture above shows that by lining up with the most forward attacker makes it difficult to determine the involvement of the attacker near the second-to-last defender. Often the difference between proper positioning and poor position is just a few feet.

WHAT IS EVEN?
A player is not in an offside position and therefore not guilty of the offense of offside if he is not nearer to the goal line than both the ball and the second-to-last defender.

Nearer is the key word in that phrase. If you are level with the ball or with the defender, you are not nearer the goal.

The line through the two players shown to the right is not the halfway line. It exists to help you align the torsos of the opposing players. The players are even. Sure, the white team's player's arm and head are in front of red team, but those body parts are not judged for offside position. It is the torso - and their torsos are level. That is not an offside position.

The only way you are going to see that minor difference is to be in position.

In the picture to the left, the red player is clearly nearer the goal line than white player, by almost a full body width.

It is not necessary to 'see daylight' between them for one to be considered nearer than the other. Allow more scoring opportunities, allow more attacking soccer and create more flow in your games. If the referee is in any doubt as to whether a player is actively involved or not, he should decide in favor of the attacker; in other words, he should refrain from whistling offside.

WHAT IS INVOLVEMENT?
The law says that a player can only be guilty of the offense of offside if he is involved in active play. That involvement may be in the form of interference with play, an opponent, or gaining an advantage by being in that position.

In the picture above, the near attacker is in an offside position but not guilty of offside since he is not involved in the play, as his teammate takes a shot directly at the goal.