A domino is a small rectangular wood or polymer block that carries an identifying pattern of spots or pips, similar to those on dice. Its other face is blank or identical to the patterned side. The most popular domino sets have 28 tiles, but larger ones exist for games involving more than one player or for players seeking to construct lengthy chains of dominoes.
Like playing cards, dominoes are grouped into suits based on the arrangement of their pips. Each suit contains six pips, four of which are marked with numbers and two that are blank. Each domino also has a number on its end, referred to as its value or rank. The rank of a tile is determined by its value on the left and right ends of the domino. For example, a domino with a 6 on its left and a 5 on its right has a rank of 2; a double-six has a rank of 12.
Dominoes are typically twice as long as they are wide. This size allows them to be easily stacked, and a domino’s stack will stand up when placed on its edge. They are commonly made from bone, silver lip ocean pearl oyster shell (mother of pearl), ivory, or a dark hardwood such as ebony, with black or white pips inlaid or painted on its surface. Polymer dominoes are also available in a variety of colors and finishes.
The most common type of domino game involves playing a layout game. Players take turns placing dominoes on the table so that the chain of pips extends in a direction or around a central point. The player who places a domino with its pips touching the end of a previous domino or a line of dominoes, either vertically or horizontally, declares a victory and wins the game.
When the first domino falls, it releases a lot of potential energy. Much of this energy converts to kinetic energy, the energy of motion, and some is transmitted to the next domino that it pushes. This energy travels from domino to domino until all the pieces are pushed over.
A domino set is used for many different types of games, ranging from simple, straightforward blocking or scoring games to elaborate arrangements with many components. Some domino games were originally developed as a way to circumvent religious proscriptions against playing cards, but they remain popular for their ease of play and interesting rules. A very popular variation on a classic card game, Concentration, is played with dominoes instead of cards and often provides an opportunity for social interaction as players compete to place all their dominoes in a row.