Domino, also known as a domino block, is a small rectangular gaming piece that has two sides marked with an arrangement of dots or blanks (called pips) similar to those on dice. Dominoes are used for playing games of chance and skill, mainly by placing them on a surface in lines and angular patterns and then knocking them over. A complete set of dominoes includes 28 pieces. Other nicknames include bones, cards, men, pieces or tiles.
The most popular commercially available domino sets are double six and double nine. These come in a box containing 28 dominoes, but larger sets do exist. These are used for games that involve many players or for longer domino chains. Most domino games are played with a single player, but some are team games.
During each round, each player in turn places one domino tile on the table. It must be placed so that its matching end touches a domino already laid down. The domino must then be connected to another domino, forming a chain that grows in size. A tile may be added to a domino in two ways: It can be played to the right or left of the initial tile, or it can be attached at a right angle. The resulting chain is called a train. A domino with a matching side to the initial tile is called a double, and additional tiles played to it must match either its long or short end.
Dominoes are arranged in a variety of different patterns, and each pattern has its own rules for playing. In general, however, the most successful players will have a strategy for laying down their dominoes so that they connect in a “domino train.” The first domino tile must be placed on an open end, and any subsequent tiles placed on that train must be matching with the same number on each of its sides.
A successful strategy may include the use of a train and other special strategies, but most players will find themselves making mistakes at some point. To minimize these errors, players should keep a written record of the previous rounds. A “sketch” or “blueprint” of a typical domino layout can also be useful.
The word domino has several meanings, including the name of a game, but it is probably best known as a metaphor for any cascade of events that begins with a small trigger and grows rapidly in scale and scope. The domino effect was popularized in political speeches by President Dwight D. Eisenhower, who cited a falling domino principle to explain the way Communist expansion would continue if America did not intervene in Vietnam. The idiom is now commonly used in non-political contexts as well. In fact, the act of writing a novel often involves considering how to create a plot that will develop into a domino effect.