A domino is a flat thumb-sized rectangular tile with one face that bears a pattern of dots or pips and the other blank or identical. Each domino has a line in the middle to divide it visually into two squares, each bearing from one to six pips or spots. A domino is numbered on both sides, so that each side has its own value (as opposed to being paired to produce a sum). The value of a domino is called its rank or weight; a higher-ranking domino has more pips than a lower-ranking domino.

There are a number of games that can be played with dominoes, including blocking games and scoring games. Some of the scoring games, such as bergen and muggins, count the total number of exposed dots on opponents’ dominoes. Others, such as domino tetris, can help students learn number recognition and counting. There are also a number of domino art forms that can be created, including straight lines, curved lines, grids that form pictures when they fall, and stacked walls.

In most domino games, each player takes turns laying down a domino in accordance with the rules of the game. If a domino cannot be laid, the player “knocks” or raps the table and play passes to the next player. Players cannot hold back a domino that they have in their hand for strategic reasons; each must play all of the dominoes they have in their hands before the end of their turn.

While there are many games that can be played with dominoes, some are more difficult to master than others. The difficulty of a game usually depends on how many dominoes are available to the players and how complex the domino pattern is that they have to follow. Some games require that all of the dominoes be used before the players can progress to the next round, while other games allow for an unlimited number of dominoes to remain in the player’s hand until the game ends.

Dominoes are typically made of bone, silver lip ocean pearl oyster shell (mother of pearl), ivory, or dark hardwoods such as ebony, with contrasting black or white pips. There are also a number of polymer and resin-based sets that are popular for children’s use because they are inexpensive, durable, and easy to assemble and clean.

The most common use for a set of dominoes is playing games. In most of these games, the objective is to be the first player to have all of their dominoes in a row. The rows are then used to form patterns and structures, such as tetris, where the dominoes are arranged in blocks that can be moved around by their edges. There are also more sophisticated arrangements that take many minutes, even hours, to complete, involving millions of tiles standing on their ends and requiring specialized blockages at regular intervals to prevent the premature toppling of larger sections of the arrangement.