Trading cards, also known as collectible cards, are small cards usually made of paperboard or thick paper that feature an image of a person, character, or object on one side and information about the subject on the other side. They are generally produced in sets and can be traded among collectors. Trading cards can serve different purposes, such as advertising, entertainment, or educational purposes, and are often associated with popular culture or sports. Collectors may seek to obtain rare or valuable cards to complete sets, display, or sell as part of a collection.