Domino is a game played with tiles that have a pattern on one side and blank or identically patterned on the other. A domino is functionally similar to playing cards, but the identity-bearing side of each piece is divided into squares marked with an arrangement of dots or pips, like those on a die, while the other two sides are blank. The most common domino set contains 28 pieces. In addition to being used to play a variety of games, dominoes are also often arranged in lines and angular patterns as decorative artwork.

The earliest known use of dominoes occurred in China in the 12th or 13th century. In the west, however, they were not recorded until the mid-18th century in Italy and France. Since then they have become a popular form of recreation. In fact, there are even Domino shows where people compete to create elaborate domino effects and reactions before a live audience.

Essentially, the purpose of a domino is to build up a chain of dominoes so that when any one of them is played, all of the others will fall over as well. A player will start the chain by placing a domino on the table. Afterward, each player will then add to it in turn by placing a tile onto the table that has the same number as one of the exposed ends of the domino that was just played.

Once the players have all drawn their tiles, they are usually arranged face down on the table so that each can only see his own, but none of the other players can see the value of their tiles. The first player to play his tile is typically determined by drawing lots or by who holds the heaviest hand. Upon being placed, the first domino is normally a double-six. The other end of the tile that was just played must then be positioned against the adjacent ends of a second domino that has the same number as the first (i.e. a 6-6).

A domino can only be connected to other dominoes in a limited number of ways, depending on the rules of the game. Usually only the long sides of a domino are considered to be open for connecting other tiles, but some games allow for additional tiles to be placed on the short ends of a double.

Most domino games are based on positional play, where each player in turn places a domino edge to edge against another in such a way that the numbers on the ends of the tiles match up, or are a certain total. Some games are designed so that the totals must be divisible by five, while others make no such restriction.

Although a variety of materials are available for dominoes, they are most commonly made from bone, silver lip ocean pearl oyster shell (mother of pearl), ivory or dark hardwood such as ebony. In modern times, there have also been sets made from synthetic materials such as marble or plastic.