A domino is a small rectangular wood or plastic block, each end marked with dots similar to those on dice. It is most often used in games with one or more players and can be a component of a puzzle or a board game. The word may also refer to a chain reaction that causes a series of dominoes to fall in a specific order.
There are many types of domino games, but most of them fall into four categories: bidding, blocking, scoring, and round games. The most popular domino games involve removing the tiles from your opponents’ hands, or blocking their play, while scoring points. Other common domino games include placing tiles in certain positions to form a total, such as in bergen and muggins. Round games are those in which the last domino played wins.
In a domino game, each tile must be placed edge-to-edge against another tile, or in a line of dominoes, in such a way that the matching ends are adjacent. The first player to place a domino begins the chain, which can run in any direction. The next player then plays a domino on the end of the previous domino, and so on. Depending on the rules of the game, the final domino in the chain can either form the highest score or be left alone.
When a domino is standing upright, it has potential energy (stored energy based on its position). When the domino falls, much of this energy is converted to kinetic energy, or energy of motion. This energy travels down the chain, just like a nerve impulse in your body, causing the rest of the dominoes to fall at an identical rate.
The size of the domino set varies, but most commonly a double-twelve (12 tiles) or double-nine (55 tiles) domino sets are used. Larger sets exist, but these are very rare. The number of pips on an end can vary as well, but most sets have between five and fifteen pips per domino.
In some domino games, the winning player is determined by counting the pips in the losing players’ hands. However, a rule variation that players often agree to employ is to count only one of the two sides of a double (i.e., 4-4 counts as only four points). This is often easier for the losers to keep track of and prevents players from “chipping out” in an attempt to steal the win. This is also the way that many game companies mark their dominoes. This is done to avoid confusion between doubles and singles and also to make the pips more easily identifiable. The most common marking is the traditional red and black dots, but some manufacturers mark their dominoes with Arabic numerals instead of pips. Some larger domino sets are even marked with both types of marks. This makes them easy to identify and a snap for children to pick up. There are also a few game variations that require the player to remember the exact placement of his dominoes in order to play correctly.