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, and were first invented in China during the Tang dynasty.
A complete set of cards is called a pack (British English), deck (American English) or set (universal), and the subset of cards held at one time by a player during a game is commonly called a hand. A pack of cards may be used for playing a variety of card games, with varying elements of skill and chance, some of which are played for money (e.g., poker and blackjack games at a casino). Playing cards are also used for illusions, cardistry, building card structures, cartomancy and memory sport.
The front (or "face") of each card carries markings that distinguish it from the other cards in the pack 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 pack to create an imperfect information scenario (that is to say, the individual values of the cards are not known to all players at all times). Usually every card will be smooth; however, some packs have braille to allow blind people to read the card number and suit.
Dedicated deck card games have sets that are used only for a specific game. The cards described in this article are used for many games and share a common origin stemming from the standards set in Mamluk Egypt. These sets divide their cards into four suits each consisting of three face cards and numbered or "pip" cards.
If you want to make mark on playing cards, infrared contact lenses can see it. so this cards mean is infrared contact lenses for marked playing cards.