What are yellow cards and red cards in soccer?

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 punitive are they for the offending team? Here's everything to know about how the rules of soccer are enforced.

What is a yellow card?

Yellow and red cards in soccer operate much like the yellow and red lights on a traffic light. Yellow serves as a warning to slow down and proceed with caution, while red signals a complete stop.

A referee holds a yellow card in the air to signal a disciplinary warning. If a player breaks a rule, a yellow card serves as a reminder to the offending player to exhibit caution going forward.

How does a player earn a yellow card?

A number of actions can result in a yellow card. A reckless tackle, arguing with an official, faking an injury, wasting time or any act of unsportsmanlike conduct can earn a yellow card.

What are the consequences of a yellow card?

Receiving two yellow cards in a single match equates to a red card and an automatic and immediate ejection.

What is a red card?

For more serious offenses, a referee uses a red card to discipline players.

How does a player earn a red card?

A player can receive a red card for a wide range of misconduct or unsportsmanlike behavior during a match. Violent actions, abusive, offensive or insulting language, spitting or deliberately denying the opposing team a goal-scoring opportunity by committing a handball foul are all offenses that can warrant a red card.

What are the consequences of a red card?

The consequences of a red card can be significantly detrimental to a team. Players who receive a red card are immediately ejected from the field of play and are unable to compete in the remainder of the match. In the FIFA World Cup , players are also banned from starting in the next match.

Once a player is ejected, the manager of the offending team may not replace them with another player. So the team must compete with one fewer player than the opposing team for the rest of the match.

What are the origins/history of the yellow and red cards in soccer?

The sport's color-coded disciplinary system was first introduced in professional soccer during the 1970 World Cup in Mexico. British referee Ken Aston's desire for a clearer display of on-field cautions and punishments brought about the colorful cards.

One interesting historical note involving yellow and red cards: During the 2006 World Cup in Germany, Portugal and the Netherlands had a testy showdown that resulted in 16 yellow cards and four red cards. Cristiano Ronaldo was forced to exit the match after suffering a knee injury on a foul that drew a yellow card.

Each team ended the match that later became known as the "Battle of Nuremberg" with just nine players.

For more soccer coverage, check out the ESPN soccer hub page for the latest news , in-depth features , scores , schedules and more.