A domino is a small rectangular wooden or plastic block with one side marked with an arrangement of dots like those on dice and the other blank or identically patterned. A domino is divided visually into two squares by a line or ridge, each of which is numbered with an arrangement of spots or “pips” from one to six in the most common variant. A domino’s value is determined by its pips, which indicate both its rank and its value as a playable tile in the game being played. The word domino is also used to describe the rules and scoring methods that govern a particular game or the process of building a domino chain, as well as to refer to the player who makes the first play.
Before a game, the players shuffle the tiles thoroughly by moving them with their hands and placing them face down on a flat playing surface. The resulting stack of shuffled tiles is called the stock or boneyard, and each player draws seven tiles from it for that game. The player who draws the heaviest tile (sometimes known as the set, the down, or the lead) makes the first play in the game. (See the article on order of play for a discussion of how to determine this ranking.)
The heaviest tile is determined by counting the number of pips on both ends of the tile (see the article on the domino system for details). Most standard sets are double-six, and some are extended to include larger numbers of pips on the ends, increasing the total number of playable tiles to more than twice this amount.
Regardless of the size and type of the set, the basic rules that govern any domino game are generally similar. The players place their tiles on the table in a line, with each player positioned so that when he plays his domino, it will touch the end of a previous domino that shows the same number as the new piece. When this happens, the chain of dominoes grows in length and continues to grow as more tiles are played on the ends of existing ones.
In addition to the normal pips on the end of the domino, some types of sets use additional pips for special purposes such as scoring. These pips are usually inlaid or painted onto the end of the tile and are often colored white, red, green or blue.
In games where the goal is to form a domino chain that reaches from one side of the table to the other, each player takes turns adding a domino to the chains. When the chains reach the desired length, one of the players calls out “stop,” and the players begin to draw their dominoes back into their hands. Then, the winning player declares a score for his victory and places his last domino on top of the final double or triple to complete the chain.