What is a yellow card?

A yellow card is typically used in sports, such as soccer or football, to indicate a warning or caution from the referee to a player. It is typically shown when a player commits a minor infraction or violation of the rules, such as a foul or unsportsmanlike conduct. If a player receives two yellow cards during a match, it can result in a red card and the player being sent off the field. Additionally, yellow cards can accumulate over multiple matches and may lead to suspensions or other disciplinary action. Outside of sports, yellow cards may also refer to warning or citation notices issued by law enforcement or other authorities.