Dominoes are flat thumb-sized blocks of wood bearing from one to six numbered dots or spots (referred to as pips) on each side. Two matching halves form each domino, and 28 such pieces make up a complete set. The number of pips on each end defines its value; a domino with more pips is “heavier,” or has higher rank, than one with fewer pips or no pips at all. In addition to their use in games, dominoes are often used for other purposes, including art, building structures and creating patterns.
The most common game of domino consists of a series of turns in which each player plays one tile on the table, positioning it so that it touches the ends of a line of dominoes already on the table. When all the tiles are laid, this configuration of dominoes is referred to as the layout or string of play. The player who makes the first move is referred to as the setter or downer, and players must follow the rules of the game to determine how they should position their dominoes.
After each player has played a domino, the remaining tiles are called the stock and may be either passed or bought, depending on the rules of the game. The player with the highest number of pips on his or her remaining tiles begins play, as determined by the rules of the specific game. If the number of pips on the remaining tiles is equal, the winner is the person with the heaviest double (see below).
There are many different types of domino games. Some involve bidding, blocking or scoring, while others simply test a player’s skill in laying down dominoes. The rules of a particular game are established by the individual players and, in most cases, must be agreed to before the game starts.
As the first domino topples, much of its potential energy is converted to kinetic energy (the energy of motion) and transmitted to the next domino in the chain. This energy continues traveling from domino to domino until the last domino falls and the sequence is completed.
When a player is unable to play a new tile, he or she calls for the stock and places the dominoes in front of him face down. The player then draws a number of tiles from the stock, and plays a tile in such a manner that it touches one of the ends of the existing chain. This is known as a misplay, and it can be penalized according to the rules of the game.
The number of pips on the remaining dominoes of the losers is counted, and the total is added to the winner’s score. Some games also employ the “heaviest double” method of scoring, in which case the player who holds the heaviest domino with the highest value is awarded points. This can be a useful way to prevent the players from colluding to reduce their points at the end of a hand or game, and is often preferred by experienced domino players.