A referee's job is to enforce the rules of the game. In soccer, referees use yellow and red cards to accomplish that task and keep the peace. But what exactly are yellow and red cards, and how ...

The yellow and red card system seen in soccer today was first introduced at the 1970 FIFA World Cup. Prior to that, referees could still caution or send off players, but there was no clear ...

But beyond that, that encounter had a decisive influence on soccer as we know it today because it led to the invention of the yellow and red cards for warnings and expulsions. The main protagonist of ...