Offside rules in football are among the most argued-over laws in the whole sport.

The longer version

The law asks whether an attacker was in an offside position at the moment the ball was played, and whether they then became involved in play. Both parts are judgement calls: the first is a freeze-frame question, the second depends on whether a player interfered with an opponent or gained an advantage from being there.

It generates disputes because it is a rare rule that punishes position rather than action, and because margins are now measured in centimetres by assistant officials. The law has been rewritten repeatedly since the nineteenth century, shifting from three defenders to two and later narrowing what counts as interfering. Video review removed many clear errors but moved the argument to where the lines are drawn.

Where this entry sits

Facts here look at the rules, equipment and odd histories behind familiar sports and games, from balls and rackets to cards, boards and playing fields. Expect small details about scoring quirks, stadium design and the long story of the Olympic Games. The full list sits on the Sports and Games page, where every entry is listed in order.