The "back of a card" refers to the reverse side of a card, which can be found in various types of cards, such as playing cards, greeting cards, or business cards. This side often features designs, logos, or additional information that complements the front. For example, a greeting card may have a decorative pattern or a personal message printed on the back. In the case of playing cards, the back typically has a uniform design that helps distinguish one deck from another. This design can be intricate or simple, often serving both aesthetic and functional purposes, such as preventing players from identifying the value of a card when it is face down.