How Dominoes Work

Like playing cards, dominoes have identifying marks on one side and blank or identically patterned surfaces on the other. The domino’s identifying mark is an arrangement of dots, or “pips,” usually arranged in two rows with six to nine pips each. Dominoes also feature a line or ridge that divides them visually into squares with two matching ends. The value of each end is determined by the number of pips. A tile placed with a pips-matching open end may be connected to any adjacent domino, forming a chain. The shape of the chain develops according to the rules of the game being played.

Most commonly, dominoes are made from clay or pressed into plastic or resin to create an almost solid, yet supple, surface. However, sets have been made from many natural materials: stone (e.g., marble, granite, or soapstone); other woods (e.g., ebony or ivory); metals (e.g., brass or pewter); ceramic clay; and even frosted glass or crystal. A domino set made from such materials generally has a more novel look and often feels heavier than those made of polymer materials.

Some domino players choose to draw their tiles on-edge instead of face up, so each player can see the value of his own dominoes at all times during gameplay. In this case, the first domino to be played is the highest-value domino in any player’s hand, for example, the double-six. If no player has the highest-value domino, then the next heaviest is played.

When the player who holds the highest-value dominoes draws his first domino, he typically places it down on the table and then starts the domino chain by placing another of his tiles against its open end. As the dominoes are stacked and connected to each other, the chain of dominoes forms a snake-like shape.

The way that the chains develop in a domino game is an integral part of the fun and provides some of the challenge. Unlike a normal playing card, dominoes are always twice as long as they are wide. This allows the chain to easily cling to and wrap around the edge of a square piece of the same size.

Most domino games allow the addition of new dominoes to an existing layout, but only if the new domino has a matching open end. A match is made when the domino’s pips connect to those on a previously-played domino. Most dominoes have open ends on all four sides, although some have only one open end.

The most common dominoes have a maximum of 12 pips on an end, but many sets have additional ends that can be added to increase this maximum. These specialized dominoes are called “extended” and are used to play larger games with more than two players. These extensions are normally available in sets of double-nine, double-12, and double-18, but more-advanced gamers might have a set of double-21 dominoes. These specialized pieces can add a dramatic element to games that would be impossible or impractical with the standard dominoes.