Domino is a small, rectangular block used as a game piece that can be stacked on end to form long lines. Each domino has an arrangement of dots, or pips, that correspond to the numbers one through nine. Dominoes are also known as bones, men, pieces, or cards and are traditionally made of a hard material like bone, silver lip oyster shell (mother of pearl), ivory, or dark hardwood such as ebony with black or white inlaid pips. A player must match the number of dots on each of two adjacent sides to play a domino. The value of a domino is determined by the number of matching pips on either side of it, and the sum of those values, called rank or weight, determines whether a player can take another turn.
The most common use of domino is to play a game of chance, in which players try to arrange the dominoes so that they form a row of all of one type of number. The first person to do so wins. The games often involve skill and strategy, but the basic rules are simple. Dominoes can be played by two or more people and are often used to help students learn about numbers and arithmetic.
When a domino is tipped over, it causes the next domino to tip over in turn, and so on, until all of the dominoes have fallen over. This is the origin of the popular phrase, “domino effect,” which refers to a situation where one action results in many subsequent actions with dramatic—and sometimes devastating—consequences.
As part of a math lesson, a teacher might ask a student to choose a domino from a stack or bag. The teacher then holds up the domino and counts the dots on each end. The class can then name an addition equation that relates the number of dots on each end to the total number of dots on the domino. The exercise is useful because it shows that the total number of dots on a domino does not depend on how it is oriented.
A more serious application of the domino principle is found in risk analysis of chemical process accidents. The domino effect can be predicted by using models based on the probability of a chain reaction. These models are a key element in risk assessment and safety evaluation.
In fiction, the domino effect can be used to create a story with an underlying theme of a chain reaction that leads to a conclusion that may not have been foreseen. This concept is especially helpful when writing a suspenseful novel, where the reader must be kept guessing what will happen next.
The word “domino” derives from the Latin verb domini, meaning to dominate or rule. In English, it first appeared in the mid-1700s and is believed to have been influenced by French words of similar meaning. Earlier, the term referred to a long, hooded cloak worn together with a mask for carnival season or at a masquerade party. It later became associated with the playing piece. The name may also have been inspired by the appearance of black dominoes contrasted against a priest’s white surplice.