A domino is a thumb-sized rectangular block with one to six dots or pips. A complete set of dominoes contains 28 such blocks. A domino is used to play games in which a player or players try to get all of their pieces laid out before their opponents. Most domino games fall into two categories: blocking games and scoring games.

Dominoes can be used to make patterns and structures, such as lines and arcs that form pictures or walls when they fall. They can also be stacked to form towers and pyramids. Many children enjoy building structures with dominoes, and some adults like to line them up in long rows and then knock them over. Some people even use dominoes to create art, such as paintings or mosaics.

The word domino is Latin for “master.” The word came to be used as a name for a game in the early 18th century, and it was popularized in England by French prisoners toward the end of that same period. The game itself probably originated in Italy and then moved to France. The word domino may have been influenced by the earlier English and Scottish usages of the word dominus, which referred to a master or a schoolmaster.

When a domino is first played on the table, it remains upright because it has inertia, which means that its mass resists motion. However, when another domino is positioned adjacent to it, the force exerted on it by the inertia of the first domino causes it to tip over. The energy from this push is transferred to the next domino, which in turn produces its own kinetic energy, and so on, until all of the dominoes are knocked over.

Although the most common domino sets contain 28 tiles, larger sets are sometimes available for games with more than four players. These “extended” sets usually contain more than three times as many tiles as a standard double-six set and allow for additional combinations of ends.

Various rules and variations govern how a domino is placed on the table. Some players prefer to “stitch up” the ends of their tiles (lay them so that the ends touch, forming a chain). Other players try to place tiles based on arithmetic properties of the pips, such as totals of lines of tiles or tile halves.

Some games allow for a single player to dominate the entire board by playing all of his or her tiles. Other games, such as chess, involve each player taking turns placing his or her tiles in order to score points.

In the earliest domino games, each player placed a domino on the table positioning it edge to edge against an adjacent tile in such a way that its exposed ends were identical (e.g., 5 to 5) or matched some specified total. Over time, this process resulted in a domino chain that gradually increased in length.