Dominoes are small, rectangular blocks of rigid material used as gaming objects. The top of each domino is marked with an arrangement of spots or dots called pips, and the other side is blank or identically patterned. Each domino belongs to one of a number of suits, which may also include a suit of blanks or zero (indicated in the listing below by an asterisk). The value of each end of a domino is determined by its number of pips, with the value of the two opposite ends of a domino being equal. The most common sets of dominoes, commercially available as a set or individually, have 28 tiles; larger sets are sometimes made that contain more than 100 tiles.

Like a deck of cards, dominoes have a variety of different games that can be played. Some of the most popular games involve forming patterns or structures using dominoes, while others focus on blocking or scoring. Dominoes can be made from many materials, but they are typically crafted from bone, silver lip ocean pearl oyster shell (mother of pearl), ivory, or a dark hardwood such as ebony, with contrasting black or white pips inlaid or painted on them. They can be molded in a shape, such as a square or circle, or made into 3-D objects such as towers or pyramids.

In general, a domino has a rectangular shape and is twice as long as it is wide; this makes them easier to stack. The pips on the domino are arranged in groups of six to give it a distinctive appearance. The most common type of Western domino has a total value of twenty-six, but there are a variety of other variations.

The simplest domino game for two players is the block game, which uses a double-six set from which each player draws seven pieces. The players alternately extend the line of play with a tile matching one of the two ends of the previous domino, and if a player cannot extend a line, they pass. The first player to win the entire block of tiles becomes the winner.

For more complex games, dominoes are commonly arranged in rows, or a matrix, to form a pattern, such as a cross or a diamond. This allows the players to place a tile in a position that will cause other dominoes to fall as a result of the interaction of its pips with those of the existing dominoes. The most common layout games use a double-six or a double-nine set, although there are other larger sets as well.

Dominoes have the potential to become a very large and complex display, but even the largest ones require only a slight nudge to fall over. This is because the dominoes have inertia, or a tendency to remain stationary when no force is applied to them.

In fiction, the domino effect is a literary device that helps authors create an engaging plot. This involves providing the reader with an explanation for why a character does something that goes against conventional societal norms. This logical reasoning must be strong enough to keep the reader engaged and believe that the protagonist’s action is justified.