Penalty cards are used in many sports as a means of warning, reprimanding or penalizing a player, coach or team official. Penalty cards are most commonly used by referees or umpires to indicate that a player has committed an offense.

Yellow cards to indicate a caution and red cards to indicate an expulsion were used for the first time in the 1970 FIFA World Cup in Mexico. The use of penalty cards has since been adopted and expanded by several sporting codes, with each sport adapting the idea to its specific set of rules or laws.

More Info: en.wikipedia.org