Dominoes is a family of tile-based games played with gaming pieces. Each domino is a rectangular tile, usually with a line dividing its face into two square ends. Each end is marked with a number of spots (also called pips or dots) or is blank. The backs of the tiles in a set are indistinguishable, either blank or having some common design. The gaming pieces make up a domino set, sometimes called a deck or pack. The traditional European domino set consists of 28 tiles, also known as pieces, bones, rocks, stones, men, cards or just dominoes, featuring all combinations of spot counts between zero and six. A domino set is a generic gaming device, similar to playing cards or dice, in that a variety of games can be played with a set. Another form of entertainment using domino pieces is the practice of domino toppling.

The earliest mention of dominoes is from Song dynasty China found in the text Former Events in Wulin by Zhou Mi (1232–1298). Modern dominoes first appeared in Italy during the 18th century, but they differ from Chinese dominoes in a number of respects, and there is no confirmed link between the two. European dominoes may have developed independently, or Italian missionaries in China may have brought the game to Europe.^: 181

The name "domino" is probably derived from the resemblance to a kind of carnival costume worn during the Venetian Carnival, often consisting of a black-hooded robe and a white mask. Despite the coinage of the word "polyomino" as a generalization, there is no connection between the word "domino" and the number 2 in any language. The most commonly played domino games are Domino Whist, Matador, and Muggins (All Fives). Other popular forms include Texas 42, Chicken Foot, Concentration, Double Fives, and Mexican Train.^{: 181–182} In Britain, the most popular league and pub game is Fives and Threes.

Dominoes have sometimes been used for divination, such as bone throwing in Chinese culture and in the African diaspora.