World Chess Championship
The World Chess Championship is played to determine the world champion in chess. Since 2014, the schedule has settled on a two-year cycle with a championship held in every year. Magnus Carlsen has been world champion since he dethroned Viswanathan Anand in 2013, he went on to defend his title against Anand in 2014, against Sergey Karjakin in 2016 and against Fabiano Caruana in 2018. The official world championship is regarded to have begun in 1886, when the two leading players in Europe and the United States, Johann Zukertort and Wilhelm Steinitz played a match. From 1886 to 1946, the champion set the terms, requiring any challenger to raise a sizable stake and defeat the champion in a match in order to become the new world champion. From 1948 to 1993, the championship was administered by the World Chess Federation. In 1993, the reigning champion broke away from FIDE, which led to the creation of the rival PCA championship; the titles were unified at the World Chess Championship 2006. Though the world championship is open to all players, there are separate events and titles for the Women's World Chess Championship, the World Junior Chess Championship, the World Senior Chess Championship.
There are faster time limit events, the World Rapid Chess Championship and the World Blitz Chess Championship. The World Computer Chess Championship is open to hardware; the concept of a world chess champion started to emerge in the first half of the 19th century, the phrase "world champion" appeared in 1845. From this time onwards various players were acclaimed as world champions, but the first contest, defined in advance as being for the world championship was the match between Steinitz and Zukertort in 1886; until 1948 world championship contests were matches arranged between the players. As a result, the players had to arrange the funding, in the form of stakes provided by enthusiasts who wished to bet on one of the players. In the early 20th century this was sometimes a barrier that prevented or delayed challenges for the title. Between 1888 and 1948 various difficulties that arose in match negotiations led players to try to define agreed rules for matches, including the frequency of matches, how much or how little say the champion had in the conditions for a title match and what the stakes and division of the purse should be.
However these attempts were unsuccessful in practice, as the same issues continued to delay or prevent challenges. The first attempt by an external organization to manage the world championship was in 1887–1889, but this experiment was not repeated. A system for managing regular contests for the title went into operation in 1948, under the control of FIDE, functioned quite smoothly until 1993. However, in that year reigning champion Kasparov and challenger Short were so dissatisfied with FIDE's arrangements for their match that they set up a break-away organization; the split in the world championship continued until the reunification match in 2006. After reunification, FIDE retains the right to organize the world championship match, stabilizing to a two-year cycle; the first match proclaimed by the players as for the world championship was the match that Wilhelm Steinitz won against Johannes Zukertort in 1886. However, a line of players regarded as the strongest in the world extends back hundreds of years beyond them, these players are sometimes considered the world champions of their time.
They include Ruy López de Segura around 1560, Paolo Boi and Leonardo da Cutri around 1575, Alessandro Salvio around 1600, Gioachino Greco around 1623. In the 18th and early 19th centuries, French players dominated, with Legall de Kermeur, François-André Danican Philidor, Alexandre Deschapelles and Louis-Charles Mahé de La Bourdonnais all regarded as the strongest players of their time. Something resembling a world championship match was the La Bourdonnais - McDonnell chess matches in 1834, in which La Bourdonnais played a series of six matches – and 85 games – against the Irishman Alexander McDonnell; the idea of a world champion goes back at least to 1840, when a columnist in Fraser's Magazine wrote, "To whom is destined the marshal's baton when La Bourdonnais throws it down, what country will furnish his successor?... At present de La Bourdonnais, like Alexander the Great, is without heir, there is room to fear the empire may be divided under a number of petty kings."After La Bourdonnais' death in December 1840, Englishman Howard Staunton's match victory over another Frenchman, Pierre Charles Fournier de Saint-Amant, in 1843 is considered to have established Staunton as the world's strongest player.
A letter quoted in The Times on 16 November 1843, but written before that, described the second Staunton vs Saint-Amant match, played in Paris in November–December 1843, as being for "the golden sceptre of Philidor." The earliest recorded use of the term "World Champion" was in 1845, when Howard Staunton was described as "the Chess Champion of England, or... the Champion of the World". The first known proposal that a contest should be defined in advance as being for recognition as the world's best player was by Ludwig Bledow in a letter to von der Lasa, written in 1846 and published in the Deutsche Schachzeitung in 1848: "... the winner of the battle in Paris should not be overly proud of his special position, since it is in Trier that the crown will first be a
A bishop is a piece in the board game of chess. Each player begins the game with two bishops. One starts between the king's knight and the king, the other between the queen's knight and the queen; the starting squares are c1 and f1 for White's bishops, c8 and f8 for Black's bishops. The bishop is limited to diagonal movement. Bishops, like all other pieces except the knight, cannot jump over other pieces. A bishop captures by occupying the square; the bishops may be differentiated according to which wing they begin on, i.e. the king's bishop and queen's bishop. As a consequence of its diagonal movement, each bishop always remains on either the white or black squares, so it is common to refer to them as light-squared or dark-squared bishops. A rook is worth about two pawns more than a bishop; the bishop has access to only half of the squares on the board, whereas all squares of the board are accessible to the rook. On an empty board, a rook always attacks fourteen squares, whereas a bishop attacks no more than thirteen and sometimes as few as seven, depending on how near it is to the center.
A king and rook can force checkmate against a lone king, while a king and bishop cannot. In general bishops are equal in strength to knights, but depending on the game situation either may have a distinct advantage. Less experienced players tend to underrate the bishop compared to the knight because the knight can reach all squares and is more adept at forking. More experienced players understand the power of the bishop. Bishops gain in relative strength towards the endgame as more pieces are captured and more open lines become available on which they can operate. A bishop can influence both wings whereas a knight is less capable of doing so. In an open endgame, a pair of bishops is decidedly superior to either a bishop and a knight, or two knights. A player possessing a pair of bishops has a strategic weapon in the form of a long-term threat to trade down to an advantageous endgame. Two bishops and king can force checkmate against a lone king. A bishop and knight can with far greater difficulty than two bishops.
In certain positions a bishop can by itself lose a move. The bishop is capable of pinning a piece, while the knight can do neither. A bishop can in some situations hinder a knight from moving. In these situations, the bishop is said to be "dominating" the knight. On the other hand, in the opening and middlegame a bishop may be hemmed in by pawns of both players, thus be inferior to a knight which can jump over them. A knight check cannot be blocked but a bishop check can. Furthermore, on a crowded board a knight has many tactical opportunities to fork two enemy pieces. A bishop can fork. One such example occurs in the position illustrated, which arises from the Ruy Lopez: 1.e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5.0-0 b5 6. Bb3 Be7?! 7.d4 d6 8.c3 Bg4 9.h3!? Bxf3 10. Qxf3 exd4 11. Qg3 g6 12. Bh6! In the middlegame, a player with only one bishop should place friendly pawns on squares of the color that the bishop cannot move to; this allows the player to control squares of both colors, allows the bishop to move among the pawns, helps fix enemy pawns on squares on which they can be attacked by the bishop.
Such a bishop is referred to as a "good" bishop. Conversely, a bishop, impeded by friendly pawns is referred to as a "bad bishop"; the black light-squared bishop in the French Defense is a notorious example of this concept. However, a "bad" bishop need not always be a weakness if it is outside its own pawn chains. In addition, having a "bad" bishop may be advantageous in an opposite-colored bishops endgame. If the bad bishop is passively placed, it may serve a useful defensive function. Although the black pawns obstruct the white bishop on e2, it has many more attacking possibilities, thus is a good bishop vis-à-vis Black's bad bishop. Black resigned after another ten moves. A bishop may be fianchettoed, for example after moving the g2 pawn to g3 and the bishop on f1 to g2; this can form a strong defense for the castled king on g1 and the bishop can exert strong pressure on the long diagonal. A fianchettoed bishop should not be given up since the resulting holes in the pawn formation may prove to be serious weaknesses if the king has castled on that side of the board.
There are nonetheless some modern opening lines where a fianchettoed bishop is given up for a knight in order to double the opponent's pawns, for example 1.d4 g6 2.c4 Bg7 3. Nc3 c5 4.d5 Bxc3+!? 5.bxc3 f5, a sharp line originated by Roman Dzindzichashvili. Giving up a fianchettoed queen bishop for a knight is less problematic. For example, in Karpov–Browne, San Antonio 1972, after 1.c4 c5 2.b3 Nf6 3. Bb2 g6?!, Karpov gave up his fianchettoed bishop with 4. Bxf6! exf6 5. Nc3, doubling Black's pawns and giving him a hole on d5. An endgame in which each player has only one bishop, one controlling the dark squares and the other the light, will result in a draw if one player has a pawn or sometimes two more than the other; the players tend to gain control of squares of opposite colors, a deadlock results. In endgames with same-colored bish
A rook is a piece in the strategy board game of chess. The piece was called the tower, marquess and comes; the term castle is considered incorrect, or old-fashioned. Each player starts the game with two rooks, one on each of the corner squares on their own side of the board; the white rooks start on squares a1 and h1, while the black rooks start on a8 and h8. The rook moves vertically, through any number of unoccupied squares; as with captures by other pieces, the rook captures by occupying the square on which the enemy piece sits. The rook participates, with the king, in a special move called castling. In general, rooks are stronger than bishops or knights and are considered greater in value than either of those pieces by nearly two pawns but less valuable than two minor pieces by a pawn. Two rooks are considered to be worth more than a queen. Winning a rook for a bishop or knight is referred to as winning the exchange. Rooks and queens are called heavy pieces or major pieces, as opposed to bishops and knights, the minor pieces.
In the opening, the rooks are blocked in by other pieces and cannot participate in the game. In that position, the rooks support each other, can more move to occupy and control the most favorable files. A common strategic goal is to place a rook on a half-open file. From this position, the rook is unexposed to risk but can exert control on every square on the file. If one file is important, a player might advance one rook on it position the other rook behind – doubling the rooks. A rook on the seventh rank is very powerful, as it threatens the opponent's unadvanced pawns and hems in the enemy king. A rook on the seventh rank is considered sufficient compensation for a pawn. In the diagrammed position from a game between Lev Polugaevsky and Larry Evans, the rook on the seventh rank enables White to draw, despite being a pawn down. Two rooks on the seventh rank are enough to force victory, or at least a draw by perpetual check. Rooks are most powerful towards the end of a game, when they can move unobstructed by pawns and control large numbers of squares.
They are somewhat clumsy at restraining enemy pawns from advancing towards promotion, unless they can occupy the file behind the advancing pawn. As well, a rook best supports a friendly pawn towards promotion from behind it on the same file. In a position with a rook and one or two minor pieces versus two rooks in addition to pawns, other pieces – Lev Alburt advises that the player with the single rook should avoid exchanging the rook for one of his opponent's rooks; the rook is a powerful piece to deliver checkmate. Below are a few examples of rook checkmates. In the medieval shatranj, the rook symbolized a chariot; the Persian word rukh means chariot, the corresponding piece in the original Indian version chaturanga has the name ratha, in modern times it's known as हाथी to hindi speaking players, while east Asian chess games such as xiangqi and shogi have names meaning chariot for the same piece. Persian war chariots were armored, carrying a driver and at least one ranged-weapon bearer, such as an archer.
The sides of the chariot were built to resemble fortified stone work, giving the impression of small, mobile buildings, causing terror on the battlefield. In the West, the rook is universally represented as a crenellated turret. One possible explanation is that when the game was imported to Italy, the Persian rukh became the Italian word rocca, from there spread in the rest of Europe. Another possible explanation is that rooks represent siege towers – the piece is called torre in Italian and Spanish. In Hungarian it is bástya and in Hebrew language it is called צריח. Another possibility is that, as chess moved to Europe long after chariot warfare had been abandoned, a different symbol was needed to represent the rook's concept of feudal power, as such the Europeans adopted a castle to represent a lord and his feudal power, further supported by the name for the rook, the "marquess", named after a nobleperson; the chariot was sometimes represented as a silhouette, a square with two points above representing the horse's heads, which may have been seen to resemble a building with arrowports to the medieval imagination.
An exception is seen in the British Museum's collection of the medieval Lewis chess pieces in which the rooks appear as stern warders or wild-eyed Berserker warriors. Rooks are similar in appearance to small castles, as a result a rook is sometimes called a "castle"; this usage was common in the past but today it is if used in chess literature or among players, except in the expression "castling". In some languages the rook is called a ship: Thai เรือ, Arm
Fairy chess piece
A fairy chess piece, variant chess piece, unorthodox chess piece, or heterodox chess piece is a chess piece not used in conventional chess but incorporated into certain chess variants and some chess problems. Fairy pieces vary in the way; because of the distributed and uncoordinated nature of unorthodox chess development, the same piece can have different names, different pieces the same name in various contexts. All are symbolised as inverted or rotated icons of the standard pieces in diagrams, the meanings of these "wildcards" must be defined in each context separately. Pieces invented for use in chess variants rather than problems sometimes instead have special icons designed for them, but with some exceptions, many of these are not used beyond the individual games they were invented for. Today's chess exists because of variations someone made to the rules of an earlier version of the game. For example, the queen we use today was once able to move only a single square in a diagonal direction, the piece was referred to as a ferz.
Today, this piece still starts next to the king, but has gained new movement and became today's queen. Thus, the ferz is now considered a non-standard chess piece. Chess enthusiasts still like to try variations of the rules and in the way pieces move. Pieces which move differently from today's standard rules are called "variant" or "fairy" chess pieces. Fairy chess pieces fall into one of three classes, although some are hybrids. Compound pieces combine the movement powers of two or more different pieces. An -leaper is a piece that moves by a fixed type of vector between its starting and destination squares. One of the coordinates of the vector'start square – arrival square' must have an absolute value m and the other one an absolute value n. A leaper captures by occupying the square. For instance, the knight is the -leaper, it is convenient to classify all fixed-distance moves as leaps, including moves to adjacent squares, because this allows all normal moves to be placed in two categories without the need to create a third category for the king and pawn.
The leaper's move cannot be blocked. Leapers are effective forking pieces; the check of a leaper cannot be parried by interposing. All orthodox chessmen except the pawn are either leapers or riders, although the rook does'hop' over its own king when it castles. In shatranj, a Persian forerunner to chess, the predecessors of the bishop and queen were leapers: the alfil is a -leaper, the ferz a -leaper; the wazir is a -leaper. The king of standard chess combines the wazir; the dabbaba is a -leaper. The alibaba combines alfil, while the squirrel can move to any square 2 units away. The'level-3' leapers are the threeleaper, camel and tripper; the giraffe is a level-4 leaper. An amphibian is a combined leaper with a larger range than any of its components, such as the frog, a --leaper. A rider is a piece that moves an unlimited distance in one direction, provided there are no pieces in the way. There are three riders in orthodox chess: the rook is a -rider. Sliders are a special case of riders. All of the riders in orthodox chess are examples of sliders.
Riders and sliders can create both skewers. One popular fairy chess rider is the nightrider, which can make an unlimited number of knight moves in any direction; the names of riders are obtained by taking the name of its base leaper and adding the suffix "rider". For example, the zebrarider is a -rider. A hopper is a piece; the hurdle can be any piece of any color. Unless it can jump over a piece, a hopper cannot move. Note that hoppers capture by taking the piece on the destination square, not by taking the hurdle; the exceptions are locusts. They are sometimes considered a type of hopper. There are no hoppers in Western chess. In xiangqi, the cannon captures as a hopper; the grasshopper moves along the same lines as a queen, hopping over another piece and landing on the square beyond it. Compound pieces combine the powers of two or more pieces; the archbishop and amazon are three popular compound pieces, combining the powers of minor orthodox chess pieces. When one of the combined pieces is a knight, the compound may be called a knighted piece.
The archbishop and amazon are the knighted bishop, knighted rook, knighted queen respectively. When one of the combined pieces is a king, the compound may be called a crowned piece; the crowned knight combines the knight with the king's moves. The dragon king of shogi is a crowned rook. Marine pieces are compound pieces consisting of a locust in the same directions. Marine pieces have names e.g. nereide, mermaid, or poseidon. Some classes of pieces come from a certain game, will have common characteristics. Examples are the pieces from a Chinese game similar to chess; the most common are the leo, pao
Checkmate is a game position in chess and other chess-like games in which a player's king is in check and there is no way to remove the threat. Checkmating the opponent wins the game. In chess, the king is never captured—the game ends as soon as the king is checkmated. In formal games, most players resign an lost game before being checkmated, it is considered bad etiquette to continue playing in a hopeless position. If a player is not in check but has no legal move it is stalemate, the game ends in a draw. A checkmating move is recorded in algebraic notation using the hash symbol "#", for example: 34. Qg7#. A checkmate may occur in as few as two moves on one side with all of the pieces still on the board, in a middlegame position, or after many moves with as few as three pieces in an endgame position; the term checkmate is, according to the Barnhart Etymological Dictionary, an alteration of the Persian phrase "shāh māt" which means "the King is helpless". Persian "māt" applies to the king but in Sanskrit "māta" pronounced "māt", applied to his kingdom "traversed, measured across, meted out" by his opponent.
Others maintain that it means "the King is dead", as chess reached Europe via the Islamic world, Arabic māta means "died" or "is dead". However, in Pashto, the word māt still exists, meaning "destroyed, broken". Moghadam traced the etymology of the word mate, it comes from a Persian verb mandan, meaning "to remain", cognate with the Latin word maneō and the Greek menō. It means "remained" in the sense of "abandoned" and the formal translation is "surprised", in the military sense of "ambushed". Sheikh is the Arabic word for the monarch. Players would announce "Sheikh". "Māt" is an Arabic adjective for dead "helpless", or "defeated". So the king is in mate when he is ambushed, at a loss, defeated, or abandoned to his fate. In modern Arabic, the word mate depicts a person who has died open-mouthed, staring and unresponsive; the words "stupefied" or "stunned" bear close correlation. So a possible alternative would be to interpret mate as "unable to respond". A king is mate means a king is unable to respond, which would correspond to there being no response that a player's king can make to their opponent's final move.
This interpretation is much closer to the original intent of the game being not to kill a king but to leave him with no viable response other than surrender, which better matches the origin story detailed in the Shahnameh. In modern parlance, the term checkmate is a metaphor for an strategic victory. In early Sanskrit chess, the king could be captured and this ended the game; the Persians introduced the idea of warning. This was done to avoid the accidental end of a game; the Persians added the additional rule that a king could not be moved into check or left in check. As a result, the king could not be captured, checkmate was the only decisive way of ending a game. Before about 1600, the game could be won by capturing all of the opponent's pieces, leaving just a bare king; this style of play is now called robado. In Medieval times, players began to consider it nobler to win by checkmate, so annihilation became a half-win for a while, until it was abandoned. Two major pieces can force checkmate on the edge of the board.
The process is to put the two pieces on adjacent ranks or files and force the king to the side of the board, where one piece keeps the king on the edge of the board while the other delivers checkmate. In the illustration, white checkmates by forcing the black king to one row at a time; the same process can be used to checkmate with two rooks, or with two queens. There are four fundamental checkmates when one side has only his king and the other side has only the minimum material needed to force checkmate, i.e. one queen, one rook, two bishops on opposite-colored squares, or a bishop and a knight. The king must help in accomplishing all of these checkmates. If the superior side has more material, checkmates are easier; the checkmate with the queen is the most common, easiest to achieve. It occurs after a pawn has queened. A checkmate with the rook is common, but a checkmate with the two bishops or with a bishop and knight occurs infrequently; the two bishop checkmate is easy to accomplish, but the bishop and knight checkmate is difficult and requires precision.
The first two diagrams show representatives of the basic checkmate positions with a queen, which can occur on any edge of the board. The exact position can vary from the diagram. In the first of the checkmate positions, the queen is directly in front of the opposing king and the white king is protecting its queen. In the second checkmate position, the kings are in opposition and the queen mates on the rank of the king. With the side with the queen to move, checkmate can be forced in at most ten moves from any starting position, with optimal play by both sides, but fewer moves are required. In positions in which a pawn has just promoted to a queen, at most nine moves are required. In the position diagrammed, White checkmates by confining the black king to a rectangle and shrinking the rectangle to force the king to the edge
In chess, the king is the most important piece. The object of the game is to threaten the opponent's king in such a way. If a player's king is threatened with capture, it is said to be in check, the player must remove the threat of capture on the next move. If this can not be done, the king is said to be in checkmate. Although the king is the most important piece, it is the weakest piece in the game until a phase, the endgame. Players can not make any move. White starts with the king on the first rank to the right of the queen. Black starts with the king directly across from the white king; the white king starts on e1 and the black king on e8. A king can move one square in any direction unless the square is occupied by a friendly piece or the move would place the king in check; as a result, opposing kings may never occupy adjacent squares, but the king can give discovered check by unmasking a bishop, rook, or queen. The king is involved in the special move of castling. In conjunction with a rook, the king may make a special move called castling, in which the king moves two squares toward one of its rooks and the rook is placed on the square over which the king crossed.
Castling is allowed only when neither the king nor the castling rook moved, no squares between them are occupied, the king is not in check, the king will not move across or end its movement on a square, under enemy attack. A king, under attack is said to be in check, the player in check must remedy the situation. There are three possible ways to remove the king from check: The king is moved to an adjacent non-threatened square. A king cannot castle to get out of check. A piece is interposed between the attacking piece to break the line of threat; the attacking piece is captured. If none of the three options are available, the player's king has been checkmated and the player loses the game. A stalemate occurs when a player, on their turn, has no legal moves, the player's king is not in check. If this happens, the king is said to have been stalemated and the game ends in a draw. A player who has little or no chance of winning will in order to avoid a loss, try to entice the opponent to inadvertently place the player's king in stalemate.
In the opening and middlegame, the king will play an active role in the development of an offensive or defensive position. Instead, a player will try to castle and seek safety on the edge of the board behind friendly pawns. In the endgame, the king emerges to play an active role as an offensive piece as well as assisting in the promotion of their remaining pawns, it is not meaningful to assign a value to the king relative to the other pieces, as it cannot be captured or exchanged. In this sense, its value could be considered infinite; as an assessment of the king's capability as an offensive piece in the endgame, it is considered to be stronger than a bishop or knight – Emanuel Lasker gave it the value of a knight plus a pawn. It is better at defending nearby pawns than the knight is, it is better at attacking them than the bishop is. Unicode defines two codepoints for king: ♔ U+2654 White Chess King ♚ U+265A Black Chess King Barden, Play better chess with Leonard Barden, Octopus Books Limited, pp. 9, 11, 12, ISBN 0-7064-0967-1 Brace, Edward R.
An Illustrated Dictionary of Chess, Hamlyn Publishing Group, p. 151, ISBN 1-55521-394-4 Lasker, Lasker's Chess Primer, Billings, ISBN 0-7134-6241-8 Ward, Endgame Play, Batsford, ISBN 0-7134-7920-5 Fianchetto variation of the King’s Indian Defence Piececlopedia: King by Fergus Duniho and Hans Bodlaender
The pawn is the most numerous piece in the game of chess, in most circumstances the weakest. It represents infantry, or more armed peasants or pikemen; each player begins a game with eight pawns, one on each square of the rank in front of the other pieces. Individual pawns are referred to by the file. For example, one speaks of "White's f-pawn" or "Black's b-pawn". Alternatively, they can be referred to by the piece which stood on that file at the beginning of the game, e.g. "White's king bishop's pawn" or "Black's queen knight's pawn". It is common to refer to a rook's pawn, meaning any pawn on the a- or h-files, a knight's pawn, a bishop's pawn, a queen's pawn, a king's pawn, a central pawn. Unlike the other pieces, pawns cannot move backwards. A pawn moves by advancing a single square, but the first time a pawn moves, it has the option of advancing two squares. Pawns may not use the initial two-square advance to capture. Any piece in front of a pawn, friend or foe, blocks its advance. In the diagram, the pawn on c4 can move to c5.
Unlike other pieces, the pawn does not capture in the same direction. A pawn captures diagonally forward one square to the right. Another unusual rule is the en passant capture, it can occur after a pawn advances two squares using its initial two-step move option, the square passed over is attacked by an enemy pawn. The enemy pawn is entitled to capture the moved pawn "in passing" – as if it had advanced only one square; the capturing pawn moves to the square over which the moved pawn passed, the moved pawn is removed from the board. The option to capture the moved pawn en passant must be exercised on the move following the double-step pawn advance, or it is lost for the remainder of the game. En passant was added in the 15th century to compensate for the newly added two-square initial move rule. Without en passant, a pawn on its initial square could safely bypass a square controlled by an advanced enemy pawn. A pawn that advances all the way to the opposite side of the board is promoted to another piece of that player's choice: a queen, bishop, or knight of the same color.
The pawn is replaced by the new piece. Since it is uncommon for a piece other than a queen to be chosen, promotion is called "queening"; when some other piece is chosen it is known as underpromotion. The piece most selected for underpromotion is a knight, used to execute a checkmate or a fork to gain a significant net increase in material. Underpromotion is used in situations where promoting to a queen would give immediate stalemate; the choice of promotion is not limited to pieces. While this extreme would never occur in practice, in game 11 of their 1927 world championship match, José Raúl Capablanca and Alexander Alekhine each had two queens in play from move 65 through move 66. While some finer sets do include an extra queen of each color, most standard chess sets do not come with additional pieces, so the physical piece used to replace a promoted pawn on the board is one, captured; when the correct piece is not available, some substitute is used: a second queen is indicated by inverting a captured rook, or a piece is borrowed from another set.
The pawn structure, the configuration of pawns on the chessboard determines the strategic flavor of a game. While other pieces can be moved to more favorable positions if they are temporarily badly placed, a poorly positioned pawn is limited in its movement and cannot be so relocated; because pawns capture diagonally and can be blocked from moving straight forward, opposing pawns can become locked in diagonal pawn chains of two or more pawns of each color, where each player controls squares of one color. In the diagram and White have locked their d- and e-pawns. Here, White has a long-term space advantage. White will have an easier time than Black in finding good squares for his pieces with an eye to the kingside. Black, in contrast, suffers from a bad bishop on c8, prevented by the black pawns from finding a good square or helping out on the kingside. On the other hand, White's central pawns are somewhat vulnerable to attack. Black can undermine the white pawn chain with an immediate...c5 and a later...f6.
Pawns on adjacent files can support each other in defense. A pawn which has no friendly pawns in adjacent files is an isolated pawn; the square in front of an isolated pawn may become an enduring weakness. Any piece placed directly in front not only blocks the advance of that pawn, but cannot be driven away by other pawns. In the diagram, Black has an isolated pawn on d5. If all the pieces except the kings and pawns were removed, the weakness of that pawn might prove fatal to Black in the endgame. In the middlegame, Black has more freedom of movement than White, may be able to trade off the isolated pawn before an endgame ensues. A pawn which cannot be blocked or captured by enemy pawns in its advance to promotion is a passed pawn. In the diagram, White has a protected passed pawn on c5 and Black has an outside passed pawn on h5. Because