Dominoes (or "dominos") generally refers to the individual or collective gaming pieces making up a domino set (sometimes called a deck or pack) or to the subcategory of tile games played with domino pieces. In the area of mathematical tilings and polyominoes, the word domino often refers to any rectangle formed from joining two congruent squares edge to edge. The traditional Sino-European domino set consists of 28 dominoes, colloquially nicknamed bones, cards, tiles, tickets, stones, or spinners. Each domino is a rectangular tile with a line dividing its face into two square ends. Each end is marked with a number of spots (also called pips) or is blank. The backs of the dominoes in a set are indistinguishable, either blank or having some common design. A domino set is a generic gaming device, similar to playing cards or dice, in that a variety of games can be played with a set.
Modern commercial domino sets are usually made of synthetic materials, such as ABS or polystyrene plastics, or Bakelite and other phenolic resins; many sets approximate the look and feel of ivory while others use colored or even translucent plastics to achieve a more contemporary look. Modern sets also commonly use a different color for the dots of each different end value (one-spots might have black pips while two-spots might be green, three red, etc.) to facilitate finding matching ends. Occasionally, one may find a domino set made of card stock like that for playing cards. Such sets are lightweight, compact and inexpensive, but like cards are more susceptible to minor disturbances such as a sudden breeze.
The traditional set of dominoes contains one unique piece for each possible combination of two ends with zero to six spots, and is known as a double-six set because the highest-value piece has six pips on each end (the "double six"). The spots from one to six are generally arranged as they are on six-sided dice, but because there are also blank ends having no spots there are seven possible faces, allowing 28 unique pieces in a double-six set.
However, this is a relatively small number especially when playing with more than four people, so many domino sets are "extended" by introducing ends with greater numbers of spots, which increases the number of unique combinations of ends and thus of pieces. Each progressively larger set increases the maximum number of pips on an end by three, so the common extended sets are double-nine, double-twelve, double-fifteen and double-eighteen. Larger sets such as double-twenty-one can theoretically exist but are rarely seen in retail stores, as identifying the number of pips on each domino becomes difficult, and a double-twenty-one set would have a staggering 253 pieces, far more than is normally necessary for most domino games even with eight players.
The oldest domino sets have been dated from around 1120. Modern dominoes, as most of the Western world knows them, however, appear to be a Chinese invention. They were apparently derived from cubic dice, which had been introduced into China from India some time in the distant past. Each domino originally represented one of the 21 results of throwing two dice. One half of each domino is set with the pips from one die and the other half contains the pips from the second die. Chinese sets also introduce duplicates of some throws and divide the dominoes into two classes: military and civil. Chinese dominoes are also longer than typical European dominoes. Over time Chinese dominoes also evolved into the tile set used to play Mah Jong, a game which swept across the United States in the early to mid 1920s and has enjoyed moderate popularity, especially in its "solitaire" form, since that time.
The early 18th century witnessed dominoes making their way to Europe, making their first appearance in Italy. The game changed somewhat in the translation from Chinese to the European culture. European domino sets contain neither class distinctions nor the duplicates that went with them. Instead, European sets contain seven additional dominoes with six of these representing the values that result from throwing a single die with the other half of the tile left blank.
Bones that share a common number of spots on one end are said to be of the same suit. In a double-six set, for example, 1–0, 1–1, 1–2, 1–3, 1–4, 1–5, and 1–6 all belong to the suit of one. All dominos, except for the doubles, belong to two suits. The 1–2, for example, belongs to the suit of one and the suit of two. All doubles belong to one suit only by this definition. An alternate definition of suit allows all dominoes to have two suits, by counting the set of all doublets as an additional suit.
These numbers may be computed quite easily using triangular numbers: for Double n dominoes, there are T(n) = (n+1)(n+2)/2 tiles and n T(n) = n(n+1)(n+2)/2 pips. Generally the most commonly used sets are Double Sixes and Double Nines, though the other three sets are more popular for games involving several players or for players looking for long domino games.
In the most common versions of the game, the tiles are shuffled face down, and each player picks seven (7) tiles. The player with the highest double leads with that double, for example "double six". If no one has it the next highest double is called - "double five?", then "double four?", etc. until the highest double in any of the players hands is played. If no player has an "opening" double, the next heaviest domino in the highest suit is called - "six - five?", "six - four?". In some versions of the game the players take turns picking dominoes from the boneyard until an opening double is picked and played; in other versions the hand is reshuffled and each player picks seven dominos.
Playing the first bone of a hand is sometimes called setting, leading, downing, or posing the first bone. Dominoes afficinadoes often call this procedure smacking the bone down. After each hand the bones are shuffled, and each player in draws the number of bones required (7). After the first hand, the winner or winning team of the previous hand is allowed to pick their dominos first, and begins by playing any domino in his or her hand.
Play generally proceeds "clockwise", but by prior consensus can proceed "counter-clockwise". The next player, and all players in turn, must play a bone with an end that matches one of the open ends of the layouts. In some versions of the games the pips or points on the end and the section to be played next to it must add up to a given number; [For example in a double six set the "sum" would be six (6), requiring a "blank" to be played next to a "6," a "1" next to a "5", a "2" next to a "4", etc.]
The stock of bones left behind, if any, is called the boneyard, and the bones therein are said to be sleeping. In draw games, players take part in the bone selection, typically drawing from the boneyard when they don't have a "match" in their hand.
Generally, if a player inadvertantly picks up and sees one or more extra dominos, those dominos becomes part of his or her hand.
In block games, players who cannot match or play, on their turn must forfeit the turn by knocking or (passing), accomplished by tapping twice on the table or by saying, "go" or "pass". In draw games, players who cannot match or play, must draw bones from the boneyard until obtaining a playable bone. If the boneyard is exhausted, the player knocks.
Play continues until one of the players has played all the dominos in his or her hand, (and calls "out!", "I win", or "domino!") and wins the hand, or until all the players are blocked and no legal plays are left. This is in some areas referred to as a lockdown or "sewed up". In a common version of the game, the next player after the block, picks up all the dominoes in the boneyard, as if trying to find the (non-existant) match. If all the players are blocked, or locked out the player with the lowest hand / pip count wins. In team play, the team with the lowest individual hand wins. In the case of a tie, the first of tied players or the first team in the play rotation wins.
In games where points are accrued, the winning player scores a point for each pip on each bone still held by each opponent, or the opposing team. If no player went out, however, the win is determined by the lightest hand; sometimes only the excess points held by opponents. A game is generally played to 100 points, the tally being kept with paper and pencil. In more common games, mainly urban rules, games are played to 150, 200, or 250 points. In some games the tally is kept by creating houses, where the beginning of the house (the first ten points) is a large +, the next ten points are O, and scoring with a 5 is a /, and are placed in the four 'corners' of the house. In some versions, if a lockdown occurs then the first person to call the lockdown will gain the other players bones and add the amount of the pips to their house.
Double 6s = 7 rounds, double 9s = 10 rounds, double 12s = 13 rounds, double 15s = 16 rounds, double 18s = 19 rounds.
A popular domino game in Texas is 42. The game is similar to the card game spades. It is played with four players paired into teams. Each player draws seven dominoes, and the dominoes are played into tricks. Each trick counts as 1 point, and any domino with a multiple of 5 dots counts toward the total of the hand. 35 points of "five count" + 7 tricks = 42 points, hence the name.
Also, in the Caribbean, there are other common games which involve four players in which the players can play as partners or as individuals. In partners, the partners sit across from each other and all hands can not be seen by the other players. The game is started by shuffling the dominoes or 'cards' and each player pulling seven cards. The double six is then played and play continues to the starter's right side. If a player can not play then he is passed and it is the next player's turn. The object is for a team to win by one of the players running out of dominoes. The winning team is awarded a point and then restart the process by shuffling and pulling a new hand and then starting with any domino either partner wishes to play. The game goes on till one team reaches six points. Double points are awarded when you get 'key'. This happens when your last card is the only card that can be played on both ends. Also when a player pulls five doubles all players put their dominoes back and pull new hands, the following game is played for 2 points and the double six is started by the player who has it. This variation is called Partners, where the other variation is called Cut-Throat, where each player plays for himself, in which all the same rules apply as in partners. This form of dominoes is most common in Jamaica and the Cayman Islands.
Other than playing games of strategy, another common pastime using domino tiles is to stand them on edge in long lines, then topple the first tile, which falls on and topples the second, which topples the third, etc., resulting in all of the tiles falling. Arrangements of millions of tiles have been made that have taken many minutes to fall. By analogy, similar phenomena of chains of small events each causing similar events leading to eventual catastrophe are called domino effects. The phenomenon also has some theoretical relevance (amplifier, digital signal, information processing), and this amounts to the theoretical possibility of building domino computers.
The Netherlands has hosted an annual domino toppling exhibition called Domino Day since 1986. The event held on November 18, 2005 knocked over 4 million dominoes. Another new record was set at 4,079,381 stones on November 17, 2006.
Dominoes are not just for games these days. Domino Art is the art of decorating domino tiles. First the domino is sprayed with an acrylic paint. Once it has dried, it is stamped with a rubber stamp and then various colors of ink are applied. Some artists drill holes in them before spraying and wire wrap the finished piece.
Dominoes are also commonly used as components in Rube Goldberg machines.