Domino is a game in which players place tiles, called dominoes, on a flat table in such a way that they form chains with matching ends. The number of matching ends is called the value of the domino, or the pips, and may range from six to zero. The tiles are normally twice as long as they are wide, and the pips are colored either black or white. A complete set of dominoes is composed of 28 such pieces. The term domino also applies to the various games played with them, which are often characterized by their linear or angular patterns.
In many cases, the dominoes are arranged on the table in a line known as the layout, string, or chain of play. The way in which the chain is formed and the pattern of dominoes that are placed is a major part of the enjoyment of the game, and the method used to determine these arrangements is generally agreed upon by the players. The arrangement of the dominoes on the table may be modified during the course of a game by changing the way in which tiles are placed, by “passing” a tile to another player, or by rearranging the tiles on the string.
Initially, the dominoes are sorted into a stock and each player takes a certain number of tiles from this stock. The players then make their turns until each has made all the plays they can. The winner of a hand or a game is then the player who has the lowest combined total of the pips on all their remaining tiles. Some players may agree to use different methods for scoring, including counting one end of a double, or not counting the pips on the two edges of a domino (see “Order of Play” and “Passing and Byeing” below).
The dominoes that are left in the stock at the conclusion of play are sometimes referred to as the deadwood. The unused tiles are returned to the stock, from which new hands or games can be opened. If a player cannot make any more plays and is therefore out of the game, they must “chip out” by placing their last domino on the table.
There are a large variety of domino sets available, each with different numbers and types of ends. Most common are double-twelve (91 tiles) and double-nine (55 tiles). In addition, a few larger sets have been created with progressively more ends to increase the number of possible combinations of tiles.
A domino set may be made from a variety of materials, including metals (such as brass or pewter), ceramic clay, and even frosted glass. In recent years, however, the majority of dominoes sold are manufactured from plastic polymers such as phenolic or melamine resins. This is because these resins have excellent mechanical and chemical properties, making them suitable for domino production. Some high-end sets of dominoes are still produced in natural materials, such as silver lip ocean pearl oyster shell (mother of pearl), bone, ivory, or a dark hardwood such as ebony.