A collectible card game (CCG), also called a trading card game (TCG) or customizable card game, is a game played using specially designed sets of playing cards. While trading cards have been around for longer, CCGs combine the appeal of collecting with strategic gameplay.

The modern concept of CCGs was first presented in Magic: The Gathering, designed by Richard Garfield and published by Wizards of the Coast in 1993. An earlier game that might be described as a collectible card game was The Base Ball Card Game produced by The Allegheny Card Co. and registered on April 5, 1904.

Each CCG system has a fundamental set of rules that describes the players' objectives, the categories of cards used in the game, and the basic rules by which the cards interact. Each card will have additional text explaining that specific card's effect on the game. They also generally represent some specific element derived from the game's genre, setting, or source material. The cards are illustrated and named for these source elements, and the card's game function may relate to the subject. For example, Magic: The Gathering is based on the fantasy genre, so many of the cards represent creatures and magical spells from that setting. In the game, a dragon is illustrated as a reptilian beast, may have the flying ability, and have formidable game statistics compared to smaller creatures.

A card game is any game using playing cards as the primary device with which the game is played, be they traditional or game-specific. Countless card games exist, including families of related games (such as poker). A small number of card games played with traditional decks have formally standardized rules, but most are folk games whose rules vary by region, culture, and person.

Many games that are not generally placed in the family of card games do in fact use cards for some aspect of their gameplay. Similarly, some games that are placed in the card game genre involve a board. The distinction is that the gameplay of a card game primarily depends on the use of the cards by players (the board is simply a guide for scorekeeping or for card placement), while board games (the principal non-card game genre to use cards) generally focus on the players' positions on the board, and use the cards for some secondary purpose.

A card game is played with a deck or pack of playing cards which are identical in size and shape. Each card has two sides, the face and the back. Normally the backs of the cards are indistinguishable. The faces of the cards may all be unique, or there can be duplicates. The composition of a deck is known to each player. In some cases several decks are shuffled together to form a single pack or shoe.

A trading card (or collectible card) is a small card, usually made out of paperboard or thick paper, which usually contains an image of a certain person, place or thing (fictional or real) and a short description of the picture, along with other text (attacks, statistics, or trivia). There is a wide variation of different types of cards. Modern cards even go as far as to include swatches of game worn memorabilia, autographs, and even DNA Hair Samples of their subjects. as to the configuration of objects, the content on the card, and even the material used to make the card.

Trading cards are traditionally associated with sports; baseball cards are especially well-known. Cards dealing with other subjects are often considered a separate category from sports cards, known as non-sports trading cards. These often feature cartoons, comic book characters, television series and film stills. In the 1990s, cards designed specifically for playing games became popular enough to develop into a distinct category, collectible card games. These tend to use either fantasy subjects or sports as the basis for game play.