One Size: 39-44
A forward is in oside position if he is between the last and the second-last defender at the moment a team mate passes the ball, unless he is in his own half of the pitch. The oside rule apeerars in 1863, every player ahead of the ball was considered to be in illegal postiion (like rugby). 1866 modification allowed forwards to have two opponents ahead at the moment of the pass. The last modification date back to 1925. The English Professional League changed the 1866 rule to favour a high scoring football: from 4700 goals in 1848 games in the 1924-25 season, 6373 goals were scored the next season in the same numbers of games.
In 1990, the rule was slightly changed in order to consider the player in line with the second-last defender in a legal position and since 2003, it is needed position and influence in the play to be in offside position.
Rest of the world: