A domino is a small rectangular block of wood, bone, or plastic, with either one or more rounded ends and marked with dots or symbols resembling those on dice. A set of these blocks, called dominoes or dominos, is used to play a variety of games that may be based on skill, chance, or both. A domino game is played by two or more people. The rules for various games differ considerably and are often localized to specific areas of the world. The word domino also means a pattern of interlocking pieces or a structure made up of such pieces.
Most domino games are based on matching the number of pips on an open end of a domino to a free end of an already-played tile. The first player sets a domino, and each subsequent player adds a new tile that matches the number of pips on an open ended of an already-played tile. This results in a line of dominoes that may be referred to as the domino string, layout, or line of play. Matching suits are usually limited to doubles and singles, though some players use a larger number of tiles such as double-nine or double-12, or even double-18.
When a domino is placed on a table, the rounded end of the domino must be facing up and toward the players. This is necessary to allow for the domino’s interaction with other tiles that will fall into place. A domino with its pips facing up and towards the players is also less likely to get dirty or smudged when a player moves it during a game.
Dominoes can be arranged to form straight lines, curves, grids that make pictures when they fall, or stacked walls. They can also be stacked to form 3D structures such as towers and pyramids. These designs are known as domino art.
In writing, a scene domino is a point that influences the direction of a story or argument. In a novel, this could be each chapter of the book, or in nonfiction it could be an argument such as an essay or a piece of research.
A domino may be made from a variety of materials including wood, ivory, silver, or bone; synthetics such as phenolic or polypropylene; and a range of metals. In the past, some sets were made from natural stone (e.g., marble or soapstone), or a combination of stones and other natural materials such as ebony and ivory. Many dominoes are now made from polymer or synthetic materials.
In the 1977 Frost/Nixon interviews, Richard Nixon defended his decision to destabilize the Salvador Allende regime in Chile on domino theory grounds. He claimed that a Communist Chile and Cuba would create a “red sandwich” that the United States could not let stand. The concept of a domino effect has also been applied to political situations such as the Cuban missile crisis, the Arab Spring, and wars in Afghanistan and Iraq.