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). When traded separately, they are known as singles. There is a wide variation of different types of cards.

Trading cards are traditionally associated with sports (baseball cards are particularly common) but can also include subjects such as Pokémon and other 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 games are mostly fantasy-based gameplay. Fantasy art cards are a subgenre of trading cards that focus on the artwork.

Trade cards are the ancestors of cigarette and food (bubble gum) cards. Some of the earliest prizes found in retail products were cigarette cards; trade cards were designed to advertise products that were inserted into paper packs of cigarettes as stiffeners to protect the contents. Allen and Ginter in the U.S. in 1886, and British company W.D. & H.O. Wills in 1888, were the first tobacco companies to print advertisements. A couple of years later, lithograph pictures on the cards with an encyclopedic variety of topics from nature to war to sports—subjects that appealed to men who smoked—began to surface as well. By 1900, there were thousands of tobacco card sets manufactured by 300 different companies. Children would stand outside of stores to ask customers who bought cigarettes for the promotional cards. Following the success of cigarette cards, trade cards were produced by manufacturers of other products and included in the product or handed to the customer by the store clerk at the time of purchase. World War II put an end to cigarette card production due to limited paper resources, and after the war cigarette cards never really made a comeback. After that collectors of prizes from retail products took to collecting tea cards in the UK and bubble gum cards in the US.

The first baseball cards were trade cards printed in the late 1860s by a sporting goods company, around the time baseball became a professional sport. Most of the baseball cards around the beginning of the 20th century came in candy and tobacco products. It was during this era that the most valuable baseball card ever printed, the T206 tobacco card featuring Honus Wagner, was produced. The T206 set, distributed by the American Tobacco Company in 1909, is considered by collectors to be the most popular set of all time. In 1933, the Goudey Gum Company of Boston issued baseball cards with players biographies on the backs and was the first to put baseball cards in bubble gum. The 1933 Goudey set remains one of the most popular and affordable vintage sets to this day. Bowman Gum of Philadelphia issued its first baseball cards in 1948.

Topps Chewing Gum, Inc., now known as "The Topps Company, Inc.", started inserting trading cards into bubble gum packs in 1950 with such topics as TV and film cowboy Hopalong Cassidy, Frank Buck from "Bring 'Em Back Alive" on big game hunts in Africa,^{[citation needed]} and All-American Football Cards. Topps produced its first baseball trading card set in 1951, with the resulting design resembling that of playing cards. Topps owner and founder Sy Berger created the first true modern baseball card set, complete with playing record and statistics, the following year in the form of 1952 Topps Baseball. This is one of the most popular sets of all time; its most valued piece was 1952 Topps Mickey Mantle #311, which is sometimes erroneously referred to as Mantle's rookie card, though he had in fact appeared in the 1951 Bowman Baseball set. On August 28, 2022, a Mickey Mantle baseball card (Topps; #311; SGC MT 9.5) was sold for $12.600 million.

Topps purchased their chief competitor, Bowman Gum, in 1956. Topps was the leader in the trading card industry from 1956 to 1980, not only in sports cards but in entertainment cards as well. Many of the top selling non-sports cards were produced by Topps, including Wacky Packages (1967, 1973–1977), Star Wars (beginning in 1977) and Garbage Pail Kids (beginning in 1985). In 1991, Topps ceased packaging gum with their baseball cards, which many collectors preferred because their cards could no longer be damaged by gum stains. The following year, in 1992, Topps ceased using heavily waxed paper to wrap their packs of cards and began using cellophane plastic exclusively, thus eliminating the possibility of wax stains on the top and bottom cards in the packs.

In an attempt to stay current with technology and digital trends, existing and new trading card companies started to create digital trading cards that lived exclusively online or as a digital counterpart of a physical card.

In 1995 Michael A. Pace produced "computer based" trading cards, utilizing a CD ROM computer system and floppy discs.