Dominoes are a type of tile game in which players place tiles on a playing surface and attempt to form domino chains that end with the same number. The number of pips (or spots) on each end of the chain determines the rank or weight of the tile. In the most common variant, a domino with two pips on each side is called a “2”; a domino with six pips on each end is called a “6-6.”
There are many variations of the game played with different numbers of pips. In addition, some sets are extended by introducing additional ends with greater numbers of spots, which increase the total number of unique combinations of ends and pieces. These include double-nine (55 tiles), double-12 (91 tiles), and double-15 (136 tiles) sets.
The earliest domino sets were made of ebony blacks and ivory faces. The word domino comes from the French words domine, meaning “cape,” and oikos, meaning “shield.”
In its simplest form, dominoes are a set of ten pieces, each of which has the same number of pips on one or both ends. The pips on the shortest end of a domino, called the spinner, are usually arranged in a single row, while the pips on the longer ends are in pairs. In this way, the dominos can be laid end to end in a single line or at right angles.
Unlike the dice and cards that are often used in these games, dominoes can be placed together to make long chains without overlapping. The longest chain is known as a snake-line and may be referred to as a “chain”. It develops gradually from the first tile to the last, depending on the layout of the table and the players’ whims.
As a strategy, a player may play only one tile at a time, and only a single number showing on it will cause a chain to grow. A chain will also grow if it is punctuated by “stitched up” ends, as in a chain of six tiles with a double on both sides, or by the end of a chain having a double-six on each side.
The goal of a player is to make his or her domino chain longer than the opponent’s chain. This is achieved by placing a tile on the table, and positioning it so that it touches one of the ends of the chain.
If the domino does not have a number on both ends, the player must place a tile to the left of that tile so that it will touch the opposite end of the chain. If the domino does have a number on both ends, the opponent must place a tile to the right of that tile so that it will touch the same end of the chain.
This strategy is a popular technique for winning many types of games and tournaments. For example, it is a key component of the “Microgame” rule of Concentration, where a domino’s total pip count is used to score. It is also a popular method for scoring in some types of trick-taking games, where a player can earn points by placing matching dominoes in a sequence, rather than by placing them on the same end.