A playing card is a piece of specially prepared heavy paper, thin cardboard, plastic-coated paper, cotton-paper blend, or thin plastic, marked with distinguishing motifs and used as one of a set for playing card games. Playing cards are typically palm-sized for convenient handling.

A complete set of cards is called a pack or deck, and the subset of cards held at one time by a player during a game is commonly called a hand. A deck of cards may be used for playing a great variety of card games, with varying elements of skill and chance, some of which are played for money. Because playing cards are standardized and commonly available, they are used for other purposes, such as illusions, cartomancy, cardistry, and building card structures.

The front (or "face") of each card carries markings that distinguish it from the other cards in the deck and determine its use under the rules of the game being played. The back of each card is identical for all cards in any particular deck, and usually of a single color or formalized design. Usually every card will be smooth; however, some decks have braille to allow blind people to read the card number and suit. The backs of playing cards are sometimes used for advertising. For most games, the cards are assembled into a deck, and their order is randomized by shuffling.