A domino is a flat thumb-sized rectangular block with one or more spots on each side. A complete set of dominoes contains 28 such blocks, and each domino is either blank or bears a number from one to six (or, occasionally, a single domino has all blanks). Dominoes are used in games whereby the players place the tiles end to end on a table, positioning them so that the exposed ends match up: each player then plays a tile which shows the same number at both ends of the line. This gradually increases the length of the chain. When the chain is completely extended the players are awarded points for the tiles in the chain, and play passes to the next player.

Dominoes can be constructed to form many different shapes and structures, including lines and curved lines, grids which build pictures when they fall, stacked walls, and 3D structures like towers and pyramids. These pieces are often used to create art, but they can also be arranged for a game of chance or as a tabletop decoration.

The most common type of domino is the double-six set, which consists of 28 tiles. Most domino sets also contain “extended” versions that introduce more pips on the ends of the tiles, increasing the total number of possible combinations. The most common extended dominoes are the double-nine set, which consists of 55 tiles, and the double-12 set, which has 91 tiles. There are also other larger extended sets such as the double-15 and double-18 sets, which exist but are seldom seen in use.

Most games played with dominoes fall into two main categories: blocking and scoring. In blocking games the players attempt to place dominoes on the table in a row which is blocked by another row of dominoes or the edge of a square. When a domino is placed on an edge of the block it triggers a sequence in which all of the other pieces in the row are knocked over, and the players continue to place more and more dominoes until all of theirs have been played and there are no more possibilities.

In scoring games each player takes turns placing a domino on the table so that its exposed ends match up with those of other tiles. If the exposed ends show a number that is the same as a previously-placed domino, the players are awarded the value of the numbers on those dominoes. This can lead to incredibly long chains of dominoes, which are then scored.

When writing a novel, a writer can think of each scene as a domino. If a scene isn’t advancing the story, or doesn’t have enough impact on the scenes that come before it, it should be eliminated. Whether a writer uses a detailed outline, or simply lays out the story as they go along using software like Scrivener, keeping this concept in mind will help them ensure that their story is clear and engaging.