A flat, thumbsized, rectangular block, usually doubled in width and bearing from one to six pips or dots: 28 such pieces form a domino set. The word domino may also refer to any of the various games played with such blocks, involving matching and placing them in lines and angular patterns.

Dominoes are normally twice as long as they are wide, making them easier to re-stack after use. Each domino has an open end on which the pips are printed; the other end is blank or bears only one pips (a double). The value of each end, indicated by the number of pips, determines the ranking and weight of the piece, with a higher ranking (and more valuable) piece having more pips.

The most common way to play domino is in a partnership with two or more people, with each player taking turns playing a tile. The partner with the highest ranked tile then begins a chain, which may extend across or around the table. A chain is completed when the player cannot place any more tiles. The player who plays the last tile wins the game, and the loser must “chip out” or play all of his remaining dominoes to a new partner (if possible).

In addition to partnerships, dominoes can be played solo, as single dominoes. The basic rules for this are generally the same as for playing in a partnership.

Another popular variation involves scoring. Rather than limiting the number of points a winning player can have, he or she is awarded a certain amount of money for each game won. Often this money is donated to a charity.

There is much creativity in domino art: straight lines or curved, grids that form pictures when the pieces fall, 3D structures like towers and pyramids. Lily Hevesh, a 20-year-old from England, began collecting dominoes when she was 9 and has since become a professional domino artist, with more than 2 million subscribers to her YouTube channel, Hevesh5.

A large part of the enjoyment of a domino set is the way it looks and feels. Traditionally, European-style dominoes were made of 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. More recently, sets have been made of materials such as ceramic clay; glass; metals like brass or pewter; and even frosted acrylic glass. These sets, which are usually heavier than those made of polymer resins, can add a more sophisticated and tactile element to the game. These also tend to be more expensive than the more common polymer sets. They are also less likely to crack or chip when dropped or handled improperly. Nevertheless, many players still prefer the traditional look and feel of a wooden or bone set. They are also more portable.