Instruct: Given a question, retrieve passages that can help answer the question.
Query: How many pieces are used in backgammon?
Backgammon is one of the oldest known board games. Its history can be traced back nearly 5,000 years to archeological discoveries in the Middle East, originally in Iran. It is a two player game where each player has fifteen pieces ("checkers") which move between twenty-four triangles ("points") according to the roll of two dice. The objective of the game is to be first to "bear off", i.e. move all fifteen checkers off the board. Backgammon is a member of the tables family, one of the oldest classes of board games.
In October 2011 World Series of Backgammon announced a partnership with the largest online gaming operator in the world, Bwin.com, for online backgammon creating bwin.com/wsob to provide an online tour with a lower buy-in to attract all levels of players. The new tour mimics the major live tournaments run by WSOB and includes a series of events, a points race and the WSOB Championship. The WSOB Champion wins the coveted Gold Cube® and an official backgammon board made by Geoffrey Parker Games and worth apparently €2400.
The popularity of backgammon surged in the mid-1960s, in part due to the charisma of Prince Alexis Obolensky who became known as "The Father of Modern Backgammon". "Obe", as he was called by friends, co-founded the International Backgammon Association, which published a set of official rules. He also established the World Backgammon Club of Manhattan, devised a backgammon tournament system in 1963, then organized the first major international backgammon tournament in March, 1964, which attracted royalty, celebrities and the press. The game became a huge fad and was played on college campuses, in discothèques and at country clubs; stockbrokers and bankers began playing at conservative men's clubs. People young and old all across the country dusted off their boards and checkers. Cigarette, liquor and car companies began to sponsor tournaments and Hugh Hefner held backgammon parties at the Playboy Mansion. Backgammon clubs were formed and tournaments were held, resulting in a World Championship promoted in Las Vegas in 1967.
Two players, "Black" and "White", take turns placing a "stone" (game piece) of their own color on a vacant "point" (intersection) of the grid on a Go board. Black plays first. If there is a large difference in skill between the players, the weaker player typically uses Black and is allowed to place two or more stones on the board to compensate for the difference (see Go handicaps). The official grid comprises 19×19 lines, though the rules can be applied to any grid size. 13×13 and 9×9 boards are popular choices to teach beginners, or for playing quick games. Once placed, a stone may not be moved to a different point.
Tak, similar to Chess and Checkers, can be played on a square board with alternating "light" and "dark" squares. In addition, Cheapass Games released a specialized hybrid board to provide a single surface for 6x6, 5x5, 4x4, and 3x3 games. For even-sized games, pieces are played on the squares (similar to a Chess board.) Odd-sized games are played on the small diamonds located at the corners and intersections of the squares (similar to a Go board.) If there is no board available, players may use an object or a temporary marker to designate the center of the board. Players must imagine the rest of the board until there are enough pieces in play to define it. The object or marker will then be removed.
There are 22 pieces in total making up a "Hive" set, with 11 pieces per player, each representing a creature and a different means of moving (the colors listed are for the third edition of the game; the first and second used full-color drawings):In addition, one or more of the expansion pieces may be optionally added to the game:In addition, the game is packaged with a travel bag (a black drawstring bag for older editions; a nylon zippered case for the current version) to make the game more portable. Given the durability of the tiles and the lack of a board, the game is marketed as a "go-anywhere" game that simply needs a relatively flat surface on which to place pieces.
The playing pieces are called "stones". One player uses the white stones and the other, black. The players take turns placing the stones on the vacant intersections ("points") of a board. Once placed on the board, stones may not be moved, but stones are removed from the board if "captured". Capture happens when a stone or group of stones is surrounded by opposing stones on all orthogonally-adjacent points. The game proceeds until neither player wishes to make another move. When a game concludes, the winner is determined by counting each player's surrounded territory along with captured stones and komi (points added to the score of the player with the white stones as compensation for playing second). Games may also be terminated by resignation. A teacher might simplify the explanation by saying to a student "you may place your stone on any point on the board, but if I surround that stone, I will remove it."
The game starts with all the pieces occupying all the squares (or holes) of the board. Only one piece may occupy a square (or hole). Similarly, in Murray's variant the colored pieces are distributed randomly throughout the board occupying all the squares (or holes).An online software variant by BrainKing called Froglet is similar to Murray's variant. The only differences are that the size of the board is smaller (only a 12 x 12 square board), the order of play among the players is determined before the game commences and only the first player may remove a piece from anywhere on the board for his or her first move followed by capturing moves by the short leap thereafter by all players, and the color distribution among pieces is different (66 green pieces, 51 yellow pieces, 21 red pieces, and 6 blue pieces) with 1 point for a green, 2 points for a yellow, 3 points for a red, and 4 points for a blue.
Season II, 2008, expanded to events in London - the UK Masters saw a 128 draw in the main event, the largest backgammon event held in the UK for 30 years; the world's largest event, the Nordic Open joined the WSOB tour for the first time and saw the Championship field increase from 78 to 153 players and finally on the 08 tour, WSOB Cannes, which recorded 155 Championship players, second only to the World Championships. The television series expanded to 15 hours and saw superstar poker and backgammon player Gus Hansen join John Clark in the commentary box. New Yorker Jessie Cantrell hosted with further contributions from experts Sander Lylloff, Falafel Natanzon and Morten Holm.
The World Backgammon Association (WBA) has been holding the biggest backgammon Tour of the circuit since 2007, the "European Backgammon Tour" (EBGT). In 2011, the WBA collaborated with the online backgammon provider Play65 for the 2011 season of the European Backgammon Tour and with "Betfair" in 2012. The 2013 season of the European Backgammon Tour featured 11 stops and 19 qualified players competing for 19,000 € in a Grand Finale in Lefkosa, Northern Cyprus. WBA also staged the "US Open" and other events around the globe. WBA has contributed to a high-stakes event called "Crowns Cup" broadcast on several TV-channels.
Equipment varies with the game. Board games, such as Go, "Monopoly" or backgammon need a board and markers. One of the oldest known board games is Senet, a game played in Ancient Egypt, enjoyed by the pharaoh Tutankhamun. Card games, such as whist, poker and Bridge have long been played as evening entertainment among friends. For these games, all that is needed is a deck of playing cards. Other games, such as bingo, played with numerous strangers, have been organised to involve the participation of non-players via gambling. Many are geared for children, and can be played outdoors, including hopscotch, hide and seek, or Blind man's bluff. The list of ball games is quite extensive. It includes, for example, croquet, lawn bowling and paintball as well as many sports using various forms of balls. The options cater to a wide range of skill and fitness levels. Physical games can develop agility and competence in motor skills. Number games such as Sudoku and puzzle games like the Rubik's cube can develop mental prowess.
"Mojo" is played with 3 pieces each and a single neutral pawn, used as a blocker, that is common to and may be moved by both players. The game starts with the pawn in the center of the board and during play, there is a choice of 2 empty spaces. Players take turns placing their 3 pieces on the board, one at a time, on any empty position, building on those already on the board, to complete and/or block winning rows. Then, continue by moving any piece (including the opponent's) or the pawn to an adjacent empty space. Players may move the pawn. Pieces and pawns may not jump over each other and the last piece or pawn moved may not be returned to its previous position. The game is over when a player has 3 same-color pieces in a row - horizontally, vertically or diagonally and is then the winner of the game.
World Series of Backgammon (WSOB) is a major televised live tour. The television shows capture the match action, jeopardy and background around some of the world’s largest backgammon tournaments, and have broadcast throughout Europe on Eurosport 1 and 2 whilst being distributed worldwide by ESPN International.
Go is an abstract strategy board game for two players, in which the aim is to surround more territory than the opponent. The game was invented in China more than 2,500 years ago and is believed to be the oldest board game continuously played to the present day. 
A 2016 survey by the International Go Federation's 75 member nations found that there are over 46 million people worldwide who know how to play Go and over 20 million current players, the majority of whom live in East Asia.
Mancala is one of the oldest known games to still be widely played today. "Mancala" is a generic name for a family of two-player turn-based strategy board games played with small stones, beans, or seeds and rows of holes or pits in the earth, a board or other playing surface. The objective is usually to capture all or some set of the opponent's pieces. Versions of the game date back to the 7th century, and evidence suggests the game existed in ancient Egypt.
This device allowed people to visualize where the half steps of the gamut were, and to visualize the interlocking positions of the hexachords (the names of which—"ut re mi fa sol la"—were taken from the hymn "Ut queant laxis"). The Guidonian hand was reproduced in numerous medieval treatises.
A pachinko machine resembles a vertical pinball machine, but is different from Western pinball in several ways. First, a pachinko machine uses small (11 mm diameter) steel balls, which are rented to the player by the owner (usually a "pachinko parlor," featuring many individual games in rows), while pinball games use a larger, captive ball. The pachinko balls are not only the active object, but are also the bet and the prize. The player loads one or more balls into the machine, then presses and releases a spring-loaded handle, which is attached to a padded hammer inside the machine, thus launching the ball into a metal track. The track guides the ball around the edge of the playing field, then when the ball loses momentum, it falls into the playing field from near the top. Some pachinko machines have a bumper to bounce the ball as it reaches the top, while other machines allow the ball to travel all the way around the field, to fall on the second time that it reaches the top.
A tennis backboard is a simple wall usually made from some kind of fiberboard and located at a tennis court. It should have a tennis net either drawn or painted at the proper height. It is designed to allow a single person to practice by hitting a tennis ball against the wall so the ball is returned, much like a second player would return it.
Board games have been known since ancient history, with the oldest records being paintings in mastabas of the First and Third Dynasties of Egypt (3100-2700 BC). The first known version of chess appeared around the 6th century in India and was called Chaturanga, played on a board of the game Ashtapada. This board was monochromatic and divided into eight columns by eight rows, with special marks called "castles" in the first, fourth, fifth, and eighth squares of the "a", "d", "e", and "h" columns, which served a function in Ashtapada, but not in Chaturanga.
Pachinko machines vary in several aspects, including decoration, music, modes and gates. The majority of modern machines have an LCD screen centered over the main start pocket. The game is played with keeping the stream of balls to the left of the screen, but many models will have their optimized ball stream to be in the center of the play field or to switch from left side to right side depending on the game mode. Vintage machines vary in pocket location and strategy with the majority having a specific center piece that usually contains win pockets.
Two competitors play with a ball, in an arena which is split into two halves with breakable blocks on both sides. The aim is to get a higher score than your opponent by breaking more blocks on your side than your opponent does. Competitors are in the form of humanoids, robots and aliens, all of which have a 'gun' of some sort enabling them to take control of the ball. The range of arenas have several pinball-style flippers which make the ball bounce off at unpredictable angles. The game can be played as one player versus a computer player (controlled with good AI for its time), or as two players competing against one another. Players can suck the ball into their gun then fire it at their blocks for points, or deliberately shoot the ball into their opponent to make them lose points. When hit, players disintegrate but instantly re-spawn with control of the ball going to the opponent.
The approach originated in TD-Gammon (1992). In backgammon, the evaluation of the game situation during self-play was learned through TD(formula_1) using a layered neural network. Four inputs were used for the number of pieces of a given color at a given location on the board, totaling 198 input signals. With zero knowledge built in, the network learned to play the game at an intermediate level.
Russian backgammon is a variant described in 1895 as: "...much in vogue in Russia, Germany, and other parts of the Continent...". Players start with no checkers on the board, and both players move in the same direction to bear off in a common home board. In this variant, doubles are more powerful: four moves are played as in standard backgammon, followed by four moves according to the difference of the dice value from 7, and then the player has another turn (with the caveat that the turn ends if any portion of it cannot be completed).
Backgammon playing pieces may be termed checkers, draughts, stones, men, counters, pawns, discs, pips, chips, or nips.
As a consequence of the reduced number of pieces, many people believe that hypergammon relies more heavily on luck than does backgammon. The lead in a game can swing very quickly. The difficulty of getting two pieces on the same point means that both players nearly always have blots on the board. The combination of the fact that bearing off can be completed with a single lucky roll of doubles and that it is nearly impossible to protect blots from being sent to the bar results in gammons being scored much more often than in backgammon.