Callum Williams wrote for the Colossus Blog:
“The offside rule was introduced in 1883 to prevent players from hanging around the goal of the opponent. The rule was drawn up by the English Football Association (FA) and stipulated that a player would be offside if the player was in front of the ball:
“When a player has kicked the ball, any one of the same side who is nearer to the opponent’s goal line is out of play and may not touch the ball himself, nor in any way whatever prevent any other player from doing so, until he is in play.”
The specific moment of being offside is judged to be when the ball is last touched by the most recent teammate passing the ball. Being in an offside position is not an offense in itself, it becomes an offense when the player in the offside position at the moment the ball is last touched or played by a teammate is deemed to be involved in active play.
It is up to the referee to decide if the player is involved in the play or not. Being actively involved in the area of play is not the same as being in the area of active play and the referee has to take into account the following when making a decision. There are three things a player cannot do:
Interfere with play
Interfere with an opponent
Gain an advantage by being in the offside position
“Interfering with play” means playing or touching the ball passed or touched by a team-mate.
The offside rule is now stipulated by the International Football Association Board of the FIFA in its rulebook called Laws of the Game. The most recent edition was updated in 2018/19 and the offside rule is discussed in chapter 11. Hence, the offside rule is also known as Law 11. Since the rule was introduced in 1883, the rule has gone through some changes.
When football was first played, the game was a cross between the game we know today and rugby. Originally, it was played by a different set of rules depending on where you went to school or where in the country you lived.
In 1883, when the Football Association drafted the first version of the Laws of The Game, it stated that no forward passes were allowed at all unless the ball was hit from behind the goal line. A football player was offside unless three players of the opposing team were in front of him or her, including the goalkeeper.
In 1925, the rule changed to ‘two opponents’ instead of three and a marked increase in the amount of goals scored occurred. Before this rule, passing was mostly done away from the opponent’s goal but when the offside rule was changed in 1925 passing became an integral part of football and, to many, the beauty of modern football was born…”