Yellow and red cards were introduced at the 1970 World Cup, inspired by traffic lights.

The inspiration for penalty cards came after a controversial 1966 World Cup quarter-final match between England and Argentina. Referee Ken Aston noticed that players and fans often misunderstood verbal cautions or dismissals. While driving through London, Aston stopped at a traffic light and realized that yellow for 'caution' and red for 'stop' were universally understood signals.Aston served as the chairman of the FIFA Referees' Committee and formally proposed the system to overcome linguistic hurdles in international matches. FIFA officially adopted the cards for the 1970 World Cup held in Mexico. The first player to receive a yellow card in World Cup history was Kakhi Asatiani of the Soviet Union during the opening match against Mexico.Despite the new system, the 1970 tournament was remarkably disciplined, as not a single player was sent off with a red card during the entire competition. The cards proved so effective that they were eventually mandated across all levels of professional football by 1982. Today, the system is a global standard used to maintain order and ensure player safety on the pitch.Psychologically, the high-visibility colors provide immediate feedback to both the athlete and the audience, reducing the likelihood of on-field confrontations. This innovation transformed sports officiating, making it more transparent and accessible to a global audience. The success of the system in football led other sports, such as volleyball and rugby, to adopt similar card-based penalty systems.