A "Yellow Card" is a warning issued to players in sports, particularly in soccer and rugby. It indicates that a player has committed a foul or unsportsmanlike behavior. If a player receives two yellow cards in a single match, they are shown a red card and must leave the game. In soccer, yellow cards are part of the disciplinary system used by referees to maintain fair play. Accumulating multiple yellow cards over a series of matches can lead to suspensions, affecting a player's availability for future games.