When the first domino topples, the others tumble in a sequence of rhythmic motion that is like the firing of neurons in your brain. This “domino effect” is a metaphor for any action that cascades out in a predictable way, generating a chain reaction that spreads from one thing to another until the desired result has been achieved.
In the case of a domino game, the outcome depends on the skill and luck of the players involved, but in general, there are certain basic rules that all games must follow. For example, a player may not play a tile unless the corresponding double has already been played; and the number of points scored by each losing player at the end of a hand or the game depends on the rules of the particular game.
Although there are many different games that can be played with domino, most of them fall into four categories: bidding games, blocking games, scoring games and round games. Each category has sub-categories that further define the rules and strategies of the game. The dominos themselves are rectangular in shape and have a line or ridge that separates two squares, each of which is marked with an arrangement of dots, similar to those on a die, but there are also some squares that are blank or identically patterned. The identity-bearing sides of a domino are often colored with white or black, but some sets have all the squares painted differently to provide color contrast and variety.
After all hands have been drawn, each player should arrange his dominoes in front of him as indicated by the rules for the particular game being played. A domino that cannot be played is called a “passing” or a “bye.” The remaining tiles, referred to as the stock, remain face down and are purchased (see the section on Buying below) later in the game, if necessary.
Most dominoes are made of bone, silver lip ocean pearl oyster shell (mother-of-pearl or MOP), ivory or a dark hardwood such as ebony, with contrasting black or white pips. However, other natural materials such as marble and granite are also used to make dominoes, and there are even sets of dominoes made of glass and crystal.
In most domino games, a line of play is formed as each player makes his plays. The pips on the open ends of each domino are considered to be ends of the line of play, and the count is determined by adding up all the pips on the ends of the dominoes played as the game progresses. A double, if not a spinner, may be played on either end of the line of play; and singles are always played lengthwise.
If there are no matching doubles available, the highest double held by a player is the starting point for the next game. Alternatively, the player holding the heaviest domino may choose to start the game. If neither of these options are available, the winner of the last game played begins the next one.