A domino is a small rectangular wood or plastic block, marked on both sides with arrangements of spots resembling those on dice. The dominoes used for games can be any size and shape, but the most common are double-six, with each end having a different value of dots, ranging from six to none. A domino is played by placing it edge-to-edge against another, allowing its numbered ends to form an alternating pattern or total. When a domino is knocked over, it sets off a chain reaction that causes other pieces to fall into place and change the underlying arrangement of pips.

The number of pips on a domino is the domino’s rank, or weight; a higher ranking domino has more pips and thus “weighs” more than a lower ranking one. In addition to rank, a domino has a value, which is its count. A domino’s count is determined by the number of open pips on the end facing the line of play, and the open end of the last domino played in the line.

Almost all domino games fit into four broad categories: bidding games, blocking games, scoring games, and round games. Several variations on these general themes exist, including games of chance and skill. Some of these variations are adaptations of card games that circumvent religious proscriptions against playing cards.

In the most common domino game, a player takes turns placing dominoes on a table or other surface. The game progresses until the players run out of dominoes, or the players decide to stop playing. The remaining dominoes are called the stock. A player may draw a domino from the stock when it is his turn. The player who draws the dominanto with the most pips seats himself at the head of the table, and then chooses whether to place it with its long or short side facing the dominoes in his row.

Domino art is a popular hobby, and there are many ways to create intricate designs with dominoes. Artists use various methods to arrange the dominoes, which can range from straight lines and curved lines to grids that form pictures when they fall, or even 3D structures such as towers and pyramids. Artists also use science to help them achieve their masterpieces. For example, an expert in domino art, Hevesh, uses gravity to her advantage by arranging the dominoes in a circular pattern so that when they are knocked over, the entire group of dominoes falls at once.

The most basic set of dominoes includes 22 tiles, but larger sets can be obtained by adding more tiles to the original set. The additional tiles allow the creation of longer lines that can be joined more easily. Adding more tiles also increases the number of possible combinations of ends, which allows for more complicated positional games. The most common extended sets are double-nine and double-12, containing 55 or 91 dominoes. Larger extensions can theoretically be created, but they are not widely used.