A domino is a small rectangular wood or plastic block, the face of which is divided into two squares by a line and marked with an arrangement of dots resembling those on dice. The word is also used to describe a game played with these blocks and a set of rules that govern its play.
Dominoes have a unique property that makes them particularly useful for teaching children about cause and effect. They are easily arranged to form lines, grids that make shapes when they fall, and even 3D structures like towers and pyramids. They can be used to create artistic displays as well. The power of a domino is also the inspiration behind a principle known as the Domino Effect, which states that one change will often trigger a chain reaction in related behaviors. For example, if a person decides to decrease the amount of sedentary leisure time that they spend each day, it may lead to a healthier eating pattern as a natural side effect.
The most common type of domino is the double-six set, which contains 28 tiles. Larger sets are available, but they are less commonly used. These larger sets may contain as many as 55 tiles. A domino is also sometimes referred to as a bone, a card, or men (plural: cards). The dominoes in a set are normally twice as long as they are wide. The dominoes are also often stacked together, with each piece resting on the end of the next tile.
Each domino has an identifying mark on one of its two faces, which is usually marked with an arrangement of dots, or pips, that range in value from six to blank. This number, which is called its rank, determines its placement in the domino set and in a specific game. The higher the rank, the more valuable the domino is.
When a player places a domino on the table, it forms a line, or string, that runs from left to right. This configuration of dominoes is called a layout, string or line of play. Each domino in the line must be played onto another one, which may be a single, double or triple. In some games, only the open ends of the dominoes count for scoring purposes.
Depending on the game, players may draw new hands if they cannot open the game with a double. Alternatively, the winner of the last game plays the first domino in the next game. If neither player holds a double, the player holding the heaviest domino begins play.
While most modern dominoes are made of polymer, some sets are made from other materials including stone (e.g., marble or granite); other types of wood (e.g., ash, oak or redwood); metals (e.g., brass or pewter); ceramic clay; and other substances. These sets have a more distinctive look and are often much heavier than their polymer counterparts. This added weight can be helpful for some games that require careful placement and positioning of the pieces.