Invented in the mid-18th century, domino is a small rectangular wood or plastic block, the face of which is divided into parts bearing from one to six pips or dots. A complete set of dominoes consists of 28 such pieces. When a domino is flipped over, its flat surface slides across that of another domino toppling it and creating a chain reaction. This action evokes the same type of force as a lightning strike or a nerve impulse firing through an axon in the brain, with a rapid transfer of energy that can be felt and heard.

Dominos are typically played by two or more people, although solo players can also enjoy the game. The basic rules for a domino game are easy to learn, and many variations exist. Some games involve a single domino, while others require multiple dominoes to be lined up in straight or angular rows. Some domino games are won by the first player to make a play, but most involve scoring or advancing along a line of dominoes.

The most common sets of dominoes feature either double six or double nine tiles, with each domino featuring a number from zero to six on its open end. Larger sets of dominoes are available, but these are usually reserved for use in tournaments and for players who like to play long domino games. Some of the most complex domino creations are made by professional builders who compete in domino shows, where a lineup of hundreds or thousands of dominoes is carefully set up to fall with the nudge of just one tile.

Each domino has a suit that corresponds to the numbers on its open ends, with each suit having a different color and symbol, such as a spade or an ace. Each suit also has a rank, or sequence of numbers from low to high, that indicates how powerful the tile is in a particular sequence. For example, a double six domino has the highest rank in the suit, followed by a double three and then a double two.

After the dominoes are shuffled, each player draws a domino from the stock and makes the first play in the game. Depending on the rules of a given game, the player with the highest double or the highest single starts the play. If a tie exists, the players draw new hands and start over.

In a domino game, the player who makes a mistake must remember his or her domino and the location of the missing piece, before making a play again. The next player then takes turn playing a domino on top of the misplayed domino, if possible.

Dominoes can be stacked in several ways, including in straight or curved lines, on a circle, on a horseshoe, or in an X shape. A X-shaped domino is sometimes called a frog. Whenever a domino is placed on a frog, it must cover all the points of the frog and leave no gap or overlap.