A jack is a playing card that typically features a young man, often depicted as a servant or a soldier. In a standard deck of cards, there are four jacks, one for each suit: hearts, diamonds, clubs, and spades. The jack is valued between the ten and queen in most card games, making it a face card along with the queen and king. In many games, the jack can have special roles or abilities. For example, in Poker, a jack can contribute to a straight or a flush, while in Rummy, it can be used as a wild card. The jack is also known as the "knave" in some historical contexts.