chess

Chess is a recreational and competitive game for two players. Sometimes called Western Chess or International Chess to distinguish it from its predecessors and other chess variants, the current form of the game emerged in Southern Europe in the second half of the 15th century after evolving from similar, much older games of Indian origin.

Today, chess is one of the world's most popular games, played by millions of people worldwide in clubs, online, by correspondence (mail and e-mail), in tournaments (amateur and professional) and informally. Aspects of art and science are found in chess composition and theory. Chess is also advocated as a way of enhancing mental prowess.

The game is played on a square chequered chessboard with 64 squares. At the start, each player ("white" and "black") controls sixteen pieces: one king, one queen, two rooks, two knights, two bishops, and eight pawns. The object of the game is to checkmate (or mate) the opponent's king, whereby the king is under immediate attack (in "check") and there is no way to remove it from attack on the next move. Theoreticians have developed extensive chess strategies and tactics since the game's inception.

The tradition of organized competitive chess started in the 16th century. The first official World Chess Champion, Wilhelm Steinitz, claimed his title in 1886; Vladimir Kramnik is the current World Champion. There are also biennial world team events called Chess Olympiads. Since the 20th century, two international organizations, the World Chess Federation and the International Correspondence Chess Federation have organized and overseen the top chess competitions and international titles.
One of the goals of early computer scientists was to create a chess-playing machine, and today's chess is deeply influenced by the abilities of current chess programs. In 1997, a match between Garry Kasparov, then World Champion, and IBM's Deep Blue chess program proved for the first time that computers are able to beat even the strongest human players. The popularity of online chess coincided with the growth of the Internet.

Rules

Chess is played on a square board of eight rows (called ranks and numbered from 1 to 8) and eight columns (called files and labeled from a to h) of squares. The colors of the sixty-four squares alternate and are referred to as light squares and dark squares. The pieces are divided into two matching sets, by convention called White and Black. Each player, referred to by the color of his pieces, begins the game with sixteen pieces: one king, one queen, two rooks, two bishops, two knights and eight pawns. The chessboard is placed with a light square at each player's right on the nearest rank, and the pieces are set out on the two ranks closest to each player, as shown in the diagram. Each queen stands on a square of its own color.

The player who is chosen to be White makes the first move. The players then alternate moving one of their own pieces (with the exception of castling, when a rook and the king are moved simultaneously). Each type of piece has its own unique method of movement. Pieces are moved to either an unoccupied square, or one occupied by an opponent's piece. Except for captures (en passant), an opponent's piece is captured and removed from play by moving a piece to the square that the enemy piece occupies. When a piece can be captured on the next move, it is said to be "threatened" or "under attack".

When a player's king is under immediate threat of capture, it is said to be in check. A player is not permitted to make any move that would place it in check. If the king is in check, the next move must take it out of check. If this is impossible, the player has been checkmated and loses the game.

Chess games do not have to end in checkmate – either player may resign if the situation looks hopeless. Games also may end in a draw (tie). A draw can occur in several situations, including draw by agreement, stalemate, threefold repetition of a position, the fifty move rule, or a draw by impossibility of checkmate (usually because of insufficient material to checkmate).

Chess can be played with a time control. This involves assigning each player a set amount of time to make moves. If a player's time runs out before the game is completed, he automatically loses. The timing ranges from up to seven hours for long games to shorter rapid chess games usually lasting 30 minutes or one hour. Even shorter is blitz chess, with a time control of three to fifteen minutes per player and bullet chess, in which the allotment is under three minutes.

The international rules of chess are described in more detail in the FIDE Handbook, section Laws of Chess.[1]

History

Many countries lay claim to the invention of chess. It is presently thought that the game originated in India,[2] since the Persian word for chess, shatranj, is derived from the Sanskrit chaturanga, i.e. "four divisions of the military", infantry, cavalry, elephants and chariots, represented respectively by pawn, knight, bishop and rook.
The first reference to chess in literature appears in Persia and dates around the 5th century AD[3] Karnamag-i Artaxshir-i Papakan. The earliest unambiguous reference in India appears to date from about 625 AD. The earliest documented chess pieces also date to the 7th century. By about 800 the game reached China and was known, with modifications, as Xiangqi. Shatranj was taken up by the Muslim world after the Islamic conquest of Persia, with the pieces largely retaining their Persian names. In Spanish "shatranj" was rendered as ajedrez, in Portuguese as xadrez, in Turkish as satranc and in Greek as zatrikion, but in the rest of Europe it was replaced by versions of the Persian shāh ("king").

The game reached Western Europe and Russia by at least three routes, the earliest being in the 9th century. By the year 1000 it had spread throughout Europe.[4] Introduced into the Iberian Peninsula by the Moors in the 10th century, it was described in a famous 13th century manuscript covering shatranj, backgammon, and dice named the Libro de los juegos.[5]

Another theory, championed by David H. Li, contends that chess arose from Xiangqi or a predecessor thereof, existing in China since the 2nd century BC.[6]
Origins of the modern game (1450–1850)

The pieces in shatranj had limited movement; the elephant or aufin (the predecessor of the modern bishop) could only move by jumping two spaces diagonally, the counselor or fers (the predecessor of the modern queen) could move only one space diagonally, pawns could not advance two spaces on their first move, and there was no castling. Also, pawns could only promote to counselor, which was the weakest piece (after the pawn), due to its limited range.[7]

Around 1200, rules started to be modified in southern Europe, and around 1475, several major changes rendered the game essentially as we know it today.[8] These modern rules for the basic moves had been adopted in Italy[9] (or in Spain according to other sources[10]): pawns gained the option of advancing two squares on their first move and the en passant capture therewith, while bishops and queens acquired their modern abilities. This made the queen the most powerful piece; consequently modern chess was referred to as "Queen's Chess" or "Mad Queen Chess".[11] These new rules quickly spread throughout western Europe, with the exception of the rules about stalemate, which varied from place to place and were finalized in the early 19th century.[12]

This was also the time when chess started to develop a corpus of theory. The oldest preserved printed chess book, Repetición de Amores y Arte de Ajedrez (Repetition of Love and the Art of Playing Chess) by Spanish churchman Luis Ramirez de Lucena was published in Salamanca in 1497.[13] Lucena and later masters of the 16th and 17th century like Portuguese Pedro Damiano, Italians Giovanni Leonardo Di Bona, Giulio Cesare Polerio and Gioachino Greco or Spanish bishop Ruy López de Segura developed elements of openings, such as the Italian Game, King's Gambit and Ruy Lopez, and started to analyze simple endgames.

In the 18th century the center of European chess life moved from the Southern European countries to France. The two most important French masters were François-André Danican Philidor, a musician by profession, who discovered the importance of pawns for chess strategy, and later Louis-Charles Mahé de La Bourdonnais who won a famous series of matches with the strongest British master of the time, Alexander McDonnell from Ireland, in 1834.[14] Centers of chess life in this period were coffee houses in big European cities like Café de la Régence in Paris[15] and Simpson's Divan in London.[16]

As the 19th century progressed, chess organization developed quickly. Many chess clubs, chess books and chess journals appeared. There were correspondence matches between cities; for example the London Chess Club played against the Edinburgh Chess Club in 1824.[17] Chess problems became a regular part of 19th century newspapers; Bernhard Horwitz, Josef Kling and Samuel Loyd composed some of the most influential problems. In 1843, the first edition of Handbuch des Schachspiels (Handbook of Chess) was published; written by German chess masters Paul Rudolf von Bilguer and Tassilo von Heydebrand und der Lasa, it was the first comprehensive manual of chess theory.

Birth of a sport (1850–1945)

The first modern chess tournament was held in London in 1851 and was won, surprisingly, by German Adolf Anderssen, relatively unknown at the time. Anderssen was hailed as the leading chess master and his brilliant, energetic — but from today's viewpoint strategically shallow — attacking style became typical for the time.[18] Sparkling games like Anderssen's Immortal game or Morphy's Opera game — both short casual games with many sacrifices — were regarded as the highest possible summit of the chess art.[19]

Deeper insight into the nature of chess battle came with two younger players. American Paul Morphy, an extraordinary chess prodigy, won against all important competitors, including Anderssen, during his short chess career between 1857 and 1863. Morphy's success stemmed from a combination of brilliant attacks and sound strategy; he intuitively knew how to prepare attacks.[20] This scheme was later reinvented and described by another strong master and theoretician, Prague-born Wilhelm Steinitz.[21]

Besides his theoretical successes, Steinitz founded another important tradition: his triumph over the leading German master Johannes Zukertort in 1886 is regarded as the first official World Chess Championship, and Steinitz the first champion. He lost his crown in 1894 to a much younger player, German mathematician Emanuel Lasker, who maintained this title for 27 years, the longest tenure of all World Champions.[22]

It took a prodigy from Cuba, José Raúl Capablanca (World champion 1921—1927), who loved simple positions and endgames, to end the German-speaking dominance in chess; he was undefeated in tournament play for eight years until 1924. His successor was Russian-French Alexander Alekhine, a strong attacking player, who died as the World champion in 1946, having briefly lost the title to Dutch player Max Euwe in 1935, before regaining it two years later.[23]

Between the two world wars, chess was revolutionized by the new theoretical school of so-called hypermodernists like Aron Nimzowitsch or Richard Réti. They denied the simple principles of the established positional school of Steinitz and Tarrasch; hypermodernists advocated controlling the center of the board with distant pieces rather than with pawns, inviting opponents to occupy the center with pawns which become objects of attack.

Since the end of 19th century, the number of annually held master tournaments and matches quickly grew. In 1914, the title of chess grandmaster was first formally conferred by Russian Tsar Nicholas II, who awarded it to five finalists of a tournament in Saint Petersburg (Lasker, Capablanca, Alekhine, Tarrasch and Marshall). This tradition was later continued by the Fédération Internationale des Échecs or World Chess Federation (FIDE), founded in 1924 in Paris. In 1927, a World Champion title for women was established; the first to hold it was Czech-English master Vera Menchik.[24]

Post-war era (1945 and later)

After the death of Alekhine, a new World Champion was sought in a tournament of elite players ruled by FIDE, who have, since then, controlled the title. The winner of the 1948 tournament, Russian Mikhail Botvinnik, started an era of Soviet dominance in the chess world. Until the end of the Soviet Union, there was only one non-Soviet champion, American Bobby Fischer (champion 1972–1975).[25]

In the previous informal system, the World Champion decided which challenger he would play for the title and the challenger was forced to seek sponsors for the match. FIDE set up a new system of qualifying tournaments and matches. The world's strongest players were seeded into "Interzonal tournaments", where they were joined by players who had qualified from "Zonal tournaments". The leading finishers in these Interzonals would go on the "Candidates" stage, which was initially a tournament, later a series of knock-out matches. The winner of the Candidates would then play the reigning champion for the title. A champion defeated in a match had a right to play a rematch a year later. This system worked on a three-year cycle.
Botvinnik participated in championship matches over a period of fifteen years.

He won the world championship tournament in 1948 and retained the title in tied matches in 1951 and 1954. In 1957, he lost to Vasily Smyslov, but regained the title in a rematch in 1958. In 1960, he lost the title to the Latvian prodigy Mikhail Tal, an accomplished tactician and attacking player. Botvinnik again regained the title in a rematch in 1961.

Following the 1961 event, FIDE abolished the automatic right of a deposed champion to a rematch, and the next champion, Armenian Tigran Petrosian, a genius of defense and strong positional player, was able to hold the title for two cycles, 1963–1969. His successor, Boris Spassky from Russia (1969–1972), was a player able to win in both positional and sharp tactical style.[26]

The next championship, the so-called Match of the Century, saw the first non-Soviet finalist since before World War II, American Bobby Fischer, who defeated his Candidates opponents by unheard-of margins and clearly won the world championship match. In 1975, however, Fischer refused to defend his title against Soviet Anatoly Karpov when FIDE refused to meet his demands, and Karpov obtained the title by default. Karpov defended his title twice against Viktor Korchnoi and dominated the 1970s and early 1980s with a string of tournament successes.[27]
Karpov's reign finally ended in 1985 at the hands of another Russian player, Garry Kasparov. Kasparov and Karpov contested five world title matches between 1984 and 1990: Kasparov narrowly retained his title each time.[28] Kasparov would proceed to dominate the chess world until his retirement in 2005, setting records for the highest FIDE rating ever and the most #1 rankings on the FIDE rating list.

In 1993, Garry Kasparov and Nigel Short broke with FIDE to organize their own match for the title and formed a competing Professional Chess Association (PCA). From then until 2006, there were two simultaneous World Champions and World Championships: the PCA or Classical champion extending the Steinitzian tradition in which the current champion plays a challenger in match format (a series of many games); the other following FIDE's new format of many players competing in a tournament to determine the champion. Kasparov lost his Classical title in 2000 to Vladimir Kramnik of Russia.
The FIDE World Chess Championship 2006 reunified the titles, when Kramnik beat the FIDE World Champion Veselin Topalov and became the undisputed World Chess Champion.[31]

Strategy and tactics

Chess strategy consists of setting and achieving long-term goals during the game — for example, where to place different pieces — while tactics concentrate on immediate maneuver. These two parts of chess thinking cannot be completely separated, because strategic goals are mostly achieved by the means of tactics, while the tactical opportunities are based on the previous strategy of play.

Because of different strategic and tactical patterns, a game of chess is usually divided into three distinct phases: Opening, usually the first 10 to 25 moves, when players develop their armies and set up the stage for the coming battle; middlegame, the developed phase of the game; and endgame, when most of the pieces are gone and kings start to take an active part in the struggle.

Fundamentals of strategy

Chess strategy is concerned with evaluation of chess positions and with setting up goals and long-term plans for the future play. During the evaluation, players must take into account the value of pieces on board, pawn structure, king safety, space, and control of key squares and groups of squares (for example, diagonals, open-files, and dark or light squares).

The most basic is to count the total value of pieces of both sides.[41] The point values used for this purpose are based on experience; usually pawns are considered worth one point, knights and bishops about three points each, rooks about five points (the value difference between a rook and a bishop being known as the exchange), and queens about nine points. In the endgame, the king is generally more powerful than a minor piece but less powerful than a rook, thus it is sometimes assigned a fighting value of four points. These basic values are then modified by other factors like position of the piece (for example, advanced pawns are usually more valuable than those on initial positions), coordination between pieces (for example, a pair of bishops usually coordinates better than the pair bishop + knight), or type of position (knights are generally better in closed positions with many pawns while bishops are more powerful in open positions).

Another important factor in the evaluation of chess positions is the pawn structure (sometimes known as the pawn skeleton), or the configuration of pawns on the chessboard.[42] Pawns being the least mobile of the chess pieces, the pawn structure is relatively static, and largely determines the strategic nature of the position. Weaknesses in the pawn structure, such as isolated, doubled or backward pawns and holes, once created, are usually permanent. Care must therefore be taken to avoid them unless they are compensated by another valuable asset (for example, by the possibility to develop an attack).

Fundamentals of tactics

In chess, tactics in general concentrate on short-term actions — so short-term that they can be calculated in advance by a human player or by a computer. The possible depth of calculation depends on the player's ability or speed of the processor. In quiet positions with many possibilities on both sides, a deep calculation is not possible, while in "tactical" positions with a limited number of forced variants, it is possible to calculate very long sequences of moves.

Simple one-move or two-move tactical actions — threats, exchanges of material, double attacks etc. — can be combined into more complicated variants, tactical maneuvers, often forced from one side or from both. Theoreticians described many elementary tactical methods and typical maneuvers, for example pins, forks, skewers, discovered attacks (especially discovered checks), zwischenzugs, deflections, decoys, sacrifices, underminings, overloadings, and interferences.[43]

A forced variant which is connected with a sacrifice and usually results in a tangible gain is named a combination.[44] Brilliant combinations — such as those in the Immortal game — are described as beautiful and are admired by chess lovers. Finding a combination is also a common type of chess puzzle aimed at development of players' skills.

Opening

A chess opening is the group of initial moves of a game (the "opening moves"). Recognized sequences of opening moves are referred to as openings and have been given names such as the Ruy Lopez or Sicilian Defense. They are catalogued in reference works such as the Encyclopedia of Chess Openings.
There are dozens of different openings, varying widely in character from quiet positional play (e.g. the Réti Opening) to very aggressive (e.g. the Latvian Gambit). In some opening lines, the exact sequence considered best for both sides has been worked out to 30–35 moves or more.[45] Professional players spend years studying openings, and continue doing so throughout their careers, as opening theory continues to evolve.

The fundamental strategic aims of most openings are similar:[46]
Development: To place (develop) the pieces (particularly bishops and knights) on useful squares where they will have an impact on the game.
Control of the center: Control of the central squares allows pieces to be moved to any part of the board relatively easily, and can also have a cramping effect on the opponent.

King safety: It is often enhanced by castling.
Pawn structure: Players strive to avoid the creation of pawn weaknesses such as isolated, doubled or backward pawns, and pawn islands.
Apart from these fundamentals, other strategic plans or tactical sequences may be employed in the opening.

Middlegame

The middlegame is the part of the game when most pieces have been developed. Because the opening theory has ended, players have to assess the position, to form plans based on the features of the positions, and at the same time to take into account the tactical possibilities in the position.[47]

Typical plans or strategical themes — for example the minority attack, that is the attack of queenside pawns against an opponent who has more pawns on the queenside — are often appropriate just for some pawn structures, resulting from a specific group of openings. The study of openings should therefore be connected with the preparation of plans typical for resulting middlegames.

Middlegame is also the phase in which most combinations occur. Middlegame combinations are often connected with the attack against the opponent's king; some typical patterns have their own names, for example the Boden's Mate or the Lasker—Bauer combination.

Another important strategical question in the middlegame is whether and how to reduce material and transform into an endgame. For example, minor material advantages can generally be transformed into victory only in an endgame, and therefore the stronger side must choose an appropriate way to achieve an ending. Not every reduction of material is good for this purpose; for example, if one side keeps a light-squared bishop and the opponent has a dark-squared one, the transformation into a bishops and pawns ending is usually advantageous for the weaker side only, because an endgame with bishops on opposite colors is likely to be a draw, even with an advantage of one or two pawns.

Endgame

The endgame (or end game or ending) is the stage of the game when there are few pieces left on the board. There are three main strategic differences between earlier stages of the game and endgame:[48]

During the endgame, pawns become more important; endgames often revolve around attempting to promote a pawn by advancing it to the eighth rank.
The king, which has to be protected in the middlegame owing to the threat of checkmate, becomes a strong piece in the endgame and it is often advisable to bring it to the center of the board where it can protect its own pawns, attack the pawns of opposite color, and hinder movement of the opponent's king.
Zugzwang, a disadvantage because the player has to make a move, is often a factor in endgames and rarely in other stages of the game.

Endgames can be classified according to the type of pieces that remain on board. Basic checkmates are positions in which one side has only a king and the other side has one or two pieces and can checkmate the opposing king, with the pieces working together with their king. King and pawn endgames involve only kings and pawns on one or both sides and the task of the stronger side is to promote one of the pawns. Other more complicated endings are classified according to the pieces on board other than kings, e.g. "rook and pawn versus rook endgame".