A deck, in the context of playing cards, refers to a set of cards used for various games. The standard deck consists of 52 cards divided into four suits: hearts, diamonds, clubs, and spades. Each suit contains 13 ranks, including numbered cards from 2 to 10, and face cards such as jack, queen, and king. Some games also use additional cards, like jokers, which can serve different purposes depending on the rules. Decks can vary in size and composition based on the game being played. For example, a poker deck typically uses the standard 52 cards, while games like Uno use a specialized deck with unique cards and rules. Players shuffle the deck before dealing cards to ensure randomness, which is essential for fair play.