In poker, a face card is any card with a picture on it. Thus, these cards are sometimes also referred to as picture cards or paint cards.
In a standard deck of 52 cards, there are 12 face cards in total. These are four kings, four queens, and four jacks. They are also referred to as broadways.
These cards depict members of the royal court and have been a part of card decks for centuries. The term face card or paint has become quite common to describe them, not just in poker but in many other games like blackjack and baccarat.
