Domino is a game of chance and skill in which players place tiles on a table and then try to match the open ends of adjacent dominoes. There are many different kinds of games played with dominoes, and rules for each game differ somewhat. Some games are designed for partnerships; others are single player games. Generally, a player’s seat is determined by lot, after the dominoes are shuffled and the stock is drawn. The player who draws the heaviest domino has first choice of seats, and then each subsequent player chooses his or her seat to the left of the previous player. The first player to play a domino must make a double (unless the rules of the game specify otherwise).
Each domino has an identity-bearing pattern on one side and is blank or identically patterned on the other. There are a variety of patterns for the pips on the domino faces, but all have the same number of spots. This number, called the count, is usually indicated on one of the faces of a domino by an arrangement of dots, similar to those used on a die. In addition to the count, each domino also has an open end. The domino with the largest open end is known as the lead, and a tile played onto it is called the down. Other terms for playing a domino include the set and the lead.
Some domino sets are “extended,” adding more ends with additional numbers of spots, to increase the total number of possible combinations of ends and thus of dominoes. The most common extended sets are double-nine, double-12, and double-18.
Most domino games are played in a line, called the line of play. This can be either lengthwise, with the dominoes joined together end to end, or across the line of play, with the dominoes played so that both sides of a double are open (either the 3-4 or 5-5 domino).
The most popular domino games on this website are played by two or more players. These games are bidding games, blocking games, scoring games, and round games. There are also several single-player domino games, and the basic instructions for those games are different from those for the multi-player games. If a player plays a domino out of turn, it is called a misplay. When this occurs, the player must either recall his or her tile or wait to play until it is correct. He or she may also forfeit the score of the mistaken domino.