Domino is a small rectangular block with either a blank side or one containing numbers of spots resembling those on dice. It can be used to play a number of games, both simple and complex. A domino is usually played on a flat surface, such as a table or floor, although some people prefer to play on a chessboard or other board with squares painted with different colors. A domino can be arranged in a variety of ways, including straight lines or curved ones, grids that form pictures, or stacked walls. It can even be made into 3D structures, such as towers and pyramids. The word domino can also refer to the game itself or the chain of events that follow when one domino falls.

The most common domino games involve blocking or scoring points, but there are many variations that have a very different character. Some of these are adaptations of card games and were popular in some countries to circumvent religious proscriptions against playing cards. Other games are more abstract, such as solitaire and trick-taking. The traditional domino set contains 28 unique pieces, since each of the seven possible combinations of two ends with zero to six spots is represented. These are called “double-six” sets, named after the highest-value piece in the set which has six pips on each end.

Most domino games require some skill to play, as the player must consider how the tiles should be arranged. In order for a domino to be played, its two matching ends must touch. Additional tiles are placed on top of the existing layout, creating a chain of dominos extending out from a single point. The rules of most games allow only certain types of tiles to be played to a given tile. A tile with no matching ends must be placed adjacent to a double, and in some games it is permissible to place a tile only against one of the long sides of a double.

A domino’s inertia makes it resist moving unless an outside force is pushing on it. The minute a domino gets a tiny nudge, though, its potential energy changes to kinetic energy and the chain reaction begins. Stephen Morris, a physicist, describes this energy conversion: When a domino stands upright it has potential energy, or stored energy based on its position. But once a little nudge causes it to fall, much of its potential energy is converted into kinetic energy, or energy of motion.

Dominoes are a familiar sight in many homes, and they have been around for centuries. The oldest known dominoes are Chinese, dating to the 12th or 13th century. They differ from European dominoes in that they have no blank ends.

When Lily Hevesh was 9 years old, she began collecting dominoes and setting them up in straight or curved lines. Her grandmother gave her a classic 28-piece set, and Hevesh loved the thrill of flicking one domino and watching it cascade down the line. Now, she is a professional domino artist who creates spectacular setups for movies and TV shows, and has a YouTube channel with more than 2 million subscribers.