What is a yellow card?
A yellow card in soccer is a caution shown by the referee for misconduct, such as a reckless foul, time-wasting or arguing. Two yellow cards in the same match lead to a red card and a sending-off.
Referees show a yellow card for offenses including unsporting behavior, persistent fouling, delaying the restart of play, dissent, failing to keep the required distance at free kicks, and entering or leaving the field without permission. Taking off a shirt to celebrate a goal also earns a yellow card.
Yellow cards build up over a competition. In many leagues and tournaments, a player who collects a certain number of yellow cards is suspended for one or more matches. This encourages players to avoid repeated fouls.
How the card system began
Yellow and red cards were introduced at the 1970 World Cup in Mexico. English referee Ken Aston came up with the idea after confusion at the 1966 World Cup, when players did not realize they had been cautioned. He was inspired by traffic lights while driving through London.
Did You Know?
Yellow cards are used in other sports too, including field hockey, rugby and handball, though their effects differ.