When someone sets a domino down, its inertia holds it there until a slight nudge causes it to tip over. When that happens, the potential energy stored in all the other dominoes becomes available to do something—namely, push on the next one. This cascade of motion is called the Domino Effect. It’s a metaphor for any action that generates a chain reaction, and it’s the essence of what makes games of domino so much fun.
There are countless games of domino, and rules vary greatly from place to place. However, some of the basic principles apply to many different types of domino. The game begins with a double-six set of 28 dominoes, which are shuffled and placed face down on the table to form the stock or boneyard. Each player draws a number of tiles from this pile, depending on the game. After all the tiles have been drawn, they are then arranged on the table and set in a line of play. This configuration of dominoes is called a layout, string, or line of play.
After all players have arranged their tiles, they make plays in turn by placing dominoes on the table matching the pips on each open end with those on the ends of the tiles already in place. This results in a domino chain that grows as each tile is played. Domino chains are often referred to as suits, and the numbers on each domino belong to particular suits. A tile with three pips on one side belongs to the suit of threes, while a tile with two pips on each side belongs to the suit of ones.
Each player must also pay attention to the direction in which a particular domino is placed. If a tile is being placed to a double, it must be positioned perpendicular to the edge of the other domino with its middle touching at the center point. The shape of a chain develops snake-like as each tile is played on its way to the other domino.
If a chain is interrupted, it must be repaired to its original state before more plays can be made. The last domino played determines the starting player in most cases, though this rule may be overridden by a specific rule in a given game. In addition, the winner of the previous game can begin play in the next.
Some games require the use of a larger domino set, such as a double-nine (55 tile) or a double-twelve (91 tile) set. These larger sets include more of each kind of domino to increase the maximum number of possible combinations of ends.
Historically, most games were positional, meaning that each domino was placed in relation to the other dominoes around it. As a result, the domino chains developed in different shapes and lengths according to the whim of each player and the limitations of the playing surface. Nevertheless, the chain effect was still very effective at building and maintaining the position of each domino in the chain.