Chess is a two-player strategy board game played on a checkered board with 64 squares arranged in an 8×8 grid.[1] The game is played by millions of people worldwide. Chess is believed to be derived from the Indian game chaturanga sometime before the 7th century. Chaturanga is also the likely ancestor of the Eastern strategy games xiangqi (Chinese chess), janggi (Korean chess), and shogi (Japanese chess). Chess reached Europe by the 9th century, due to the Umayyad conquest of Hispania. The pieces assumed their current powers in Spain in the late 15th century; the modern rules were standardized in the 19th century.
Play involves no hidden information. Each player begins with 16 pieces: one king, one queen, two rooks, two knights, two bishops, and eight pawns. Each piece type moves differently, with the most powerful being the queen and the least powerful the pawn. The objective is to checkmate[note 1] the opponent's king by placing it under an inescapable threat of capture. To this end, a player's pieces are used to attack and capture the opponent's pieces, while supporting each other. During the game, play typically involves exchanging pieces for the opponent's similar pieces, and finding and engineering opportunities to trade advantageously or to get a better position. In addition to checkmate, a player wins the game if the opponent resigns, or (in a timed game) runs out of time. There are also several ways that a game can end in a draw
The first generally recognized World Chess Champion, Wilhelm Steinitz, claimed his title in 1886. Since 1948, the World Championship has been regulated by the Fédération Internationale des Échecs (FIDE), the game's international governing body. FIDE also awards life-time master titles to skilled players, the highest of which is Grandmaster (GM). Many national chess organizations have a title system of their own. FIDE also organizes the Women's World Championship, the World Junior Championship, the World Senior Championship, the Blitz and Rapid World Championships, and the Chess Olympiad, a popular competition among international teams. FIDE is a member of the International Olympic Committee, which can be considered recognition of chess as a sport.[3] Several national sporting bodies (e.g. the Spanish Consejo Superior de Deportes[4]) also recognize chess as a sport. Chess was included in the 2006 and 2010 Asian Games. There is also a Correspondence Chess World Championship and a World Computer Chess Championship. Online chess has opened amateur and professional competition to a wide and varied group of players.
Since the second half of the 20th century, chess engines have been programmed to play with increasing success, to the point where the strongest programs play at a higher level than the best human players. Since the 1990s, computer analysis has contributed significantly to chess theory, particularly in the endgame. The IBM computer Deep Blue was the first machine to overcome a reigning World Chess Champion in a match when it defeated Garry Kasparov in 1997. The rise of strong chess engines runnable on hand-held devices has led to increasing concern about cheating during tournaments.
There are many variants of chess that utilize different rules, pieces, or boards. One of these, Chess960, has gained widespread popularity as well as some FIDE recognition.
Rules
Main article: Rules of chess
The rules of chess are published by FIDE (Fédération Internationale des Échecs), chess's international governing body, in its Handbook.[5] Rules published by national governing bodies, or by unaffiliated chess organizations, commercial publishers, etc., may differ. FIDE's rules were most recently revised in 2017.
Setup

By convention, chess game pieces are divided into white and black sets. Each set consists of 16 pieces: one king, one queen, two rooks, two bishops, two knights, and eight pawns. The pieces are set out as shown in the diagram and photo. The players of the sets are referred to as White and Black, respectively.
The game is played on a square board of eight rows (called ranks, denoted 1 to 8 from bottom to top according to White's perspective) and eight columns (called files, denoted a to h from left to right according to White's perspective). The 64 squares alternate in color and are referred to as light and dark squares. The chessboard is placed with a light square at the right-hand corner nearest to each player. Thus, each queen starts on a square of its own color (the white queen on a light square; the black queen on a dark square). 
Movement
In competitive games, the colors are allocated by the organizers; in informal games, the colors are usually decided randomly, for example by coin toss, or by one player's concealing a white and black pawn in either hand and having the opponent choose. White moves first, after which players alternate turns, moving one piece per turn (except for castling, when two pieces are moved). A piece is moved to either an unoccupied square or one occupied by an opponent's piece, which is captured and removed from play. With the sole exception of en passant, all pieces capture by moving to the square that the opponent's piece occupies.
Moving is compulsory; it is illegal to skip a turn, even when having to move is detrimental. A player may not make any move that would put or leave the player's own king in check. If the player to move has no legal move, the game is over; the result is either checkmate (a loss for the player with no legal move) if the king is in check, or stalemate (a draw) if the king is not.
Each piece has its own way of moving. In the diagrams, the dots mark the squares to which the piece can move if there are no intervening piece(s) of either color (except the knight, which leaps over any intervening pieces).
- The king moves one square in any direction. The king also has a special move called castling that involves also moving a rook.
- A rook can move any number of squares along a rank or file, but cannot leap over other pieces. Along with the king, a rook is involved during the king's castling move.
- A bishop can move any number of squares diagonally, but cannot leap over other pieces.
- The queen combines the power of a rook and bishop and can move any number of squares along a rank, file, or diagonal, but cannot leap over other pieces.
- A knight moves to any of the closest squares that are not on the same rank, file, or diagonal. (Thus the move forms an "L"-shape: two squares vertically and one square horizontally, or two squares horizontally and one square vertically.) The knight is the only piece that can leap over other pieces.
- A pawn can move forward to the unoccupied squ
are immediately in front of it on the same file, or on its first move it can advance two squares along the same file, provided both squares are unoccupied (black dots in the diagram); or the pawn can capture an opponent's piece on a square diagonally in front of it on an adjacent file, by moving to that square (black "x"s). A paw
- n has two special moves: the en passant capture and promotion.






Castling
Main article: Castling
Once in every game, each king can make a special move, known as castling. Castling consists of moving the king two squares along the first rank toward a rook (that is on the player's first rank and then placing the rook on the last square that the king just crossed. Castling is permissible if the following conditions are met:[6]
- Neither the king nor the rook has previously moved during the game.
- There are no pieces between the king and the rook.
- The king cannot be in check, nor can the king pass through any square that is under attack by an enemy piece, or move to a square that would result in check. (Note that castling is permitted if the rook is under attack, or if the rook crosses an attacked square.)

En passant
Main article: En passant
When a pawn makes a two-step advance from its starting position and there is an opponent's pawn on a square next to the destination square on an adjacent file, then the opponent's pawn can capture it en passant ("in passing"), moving to the square the pawn passed over. This can be done only on the very next turn; otherwise the right to do so is forfeited. For example, in the animated diagram, the black pawn advances two steps from g7 to g5, and the white pawn on f5 can take it en passant on g6 (but only on White's next move).
Promotion
When a pawn advances to the eighth rank, as a part of the move it is promoted and must be exchanged for the player's choice of queen, rook, bishop, or knight of the same color. Usually, the pawn is chosen to be promoted to a queen, but in some cases another piece is chosen; this is called underpromotion. In the animated diagram, the pawn on c7 can be advanced to the eighth rank and be promoted. There is no restriction on the piece promoted to, so it is possible to have more pieces of the same type than at the start of the game (e.g., two or more queens).
Check
When a king is under immediate attack by one or two of the opponent's pieces, it is said to be in check. A move in response to a check is legal only if it results in a position where the king is no longer in check. This can involve capturing the checking piece; interposing a piece between the checking piece and the king (which is possible only if the attacking piece is a queen, rook, or bishop and there is a square between it and the king); or moving the king to a square where it is not under attack. Castling is not a permissible response to a check.
The object of the game is to checkmate the opponent; this occurs when the opponent's king is in check, and there is no legal way to remove it from attack. It is never legal for a player to make a move that puts or leaves the player's own king in check. In casual games it is common to announce "check" when putting the opponent's king in check, but this is not required by the rules of chess, and is not usually done in tournaments.

End of the game
Win
Games can be won in the following ways:
- Checkmate: The player whose turn it is to move is in check and has no legal move to escape check.
- Resignation: Either player may resign, conceding the game to the opponent.[7] It is usually considered poor etiquette to play on in a hopeless position, and for this reason high-level games rarely end in checkmate.
- Win on time: In games with a time control, a player wins if the opponent runs out of time, even if the opponent has a superior position, as long as the player has a theoretical possibility to checkmate the opponent.
- Forfeit: A player who cheats, violates the rules, or violates the rules specified for the particular tournament, can be forfeited. In high-level tournaments, players have been forfeited for such things as:
- arriving late for the game (even by a matter of seconds);
- receiving a call or text on a cell phone;
- refusing to undergo a drug test;
- refusing to undergo a body search for electronic devices;
- unsporting behavior (e.g. refusing to shake hands with the opponent).
Draw
There are several ways games can end in a draw:
- Draw by agreement: Draws are most commonly reached by mutual agreement between the players. The correct procedure is to verbally offer the draw, make a move, then start the opponent's clock. Traditionally, players have been allowed to agree to a draw at any point in the game, occasionally even without playing a move; in recent years efforts have been made to discourage short draws, for example by forbidding draw offers before move thirty.
- Stalemate: The player whose turn it is to move has no legal move and is not in check.
- Threefold repetition of position: This most commonly occurs when neither side is able to avoid repeating moves without incurring a disadvantage. In this situation, either player can claim a draw; this requires the players to keep a valid written record of the game so that the claim can be verified by the arbiter if challenged. The three occurrences of the position need not occur on consecutive moves for a claim to be valid. FIDE rules make no mention of perpetual check; this is merely a specific type of draw by threefold repetition.
- Fifty-move rule: If during the previous 50 moves no pawn has been moved and no capture has been made, either player can claim a draw. There are several known endgames where it is possible to force a mate but it requires more than 50 moves before a pawn move or capture is made; examples include some endgames with two knights against a pawn and some pawnless endgames such as queen against two bishops. Historically, FIDE has sometimes revised the fifty-move rule to make exceptions for these endgames, but these have since been repealed. Some correspondence chess organizations do not enforce the fifty-move rule.[note 2]
- Fivefold repetition of position: Similar to the threefold-repetition rule, but in this case neither player needs to claim the draw; thus a tournament director can intervene and declare the game to be drawn. This is a relatively recent (2014) addition to the FIDE rules.
- Seventy-five-move rule: Similar to the fifty-move rule; however, if the final move in the sequence resulted in checkmate, this takes precedence. As with the fivefold repetition rule, this applies independently of claims by the players, and allows a tournament director to intervene. This rule likewise is a recent addition to the FIDE rules.
- Insufficient material: If neither player has a theoretical possibility to checkmate the opponent; for example, if a player has only the king and a knight, and the opponent has only the king, checkmate is impossible and the game is drawn by this rule. On the other hand, if both players still have a knight there is a highly unlikely yet theoretical possibility of checkmate, so this rule does not apply.
- Draw on time: In games with a time control, the game is drawn if a player is out of time and the opponent has no theoretical possibility to checkmate the player.
In competition, chess games are played with a time control. If a player's time runs out before the game is completed, the game is automatically lost (provided the opponent has enough pieces left to deliver checkmate). The duration of a game ranges from long (or "classical") games which can take up to seven hours (even longer if adjournments are permitted) to bullet chess (under 3 minutes per player for the entire game). Intermediate between these are rapid chess games, lasting between 20 minutes and two hours per game, a popular time control in amateur weekend tournaments.
Time is controlled using a chess clock that has two displays, one for each player's remaining time. Analog chess clocks have been largely replaced by digital clocks, which allow for time controls with increments.
Time controls are also enforced in correspondence chess competition. A typical time control is 50 days for every 10 moves.

History
Predecessors
Chess is believed to have originated in Eastern India, c. 280–550,[9] in the Gupta Empire,[10][11][12][13] where its early form in the 6th century was known as chaturaṅga (Sanskrit: चतुरङ्ग), literally four divisions [of the military] – infantry, cavalry, elephants, and chariotry, represented by the pieces that would evolve into the modern pawn, knight, bishop, and rook, respectively. Thence it spread eastward and westward along the Silk Road. The earliest evidence of chess is found in the nearby Sassanid Persia around 600, where the game came to be known by the name chatrang. Chatrang was taken up by the Muslim world after the Islamic conquest of Persia(633–44), where it was then named shatranj, with the pieces largely retaining their Persian names. In Spanish "shatranj" was rendered as ajedrez ("al-shatranj"), in Portuguese as xadrez, and in Greek as ζατρίκιον (zatrikion, which comes directly from the Persian chatrang),[14] but in the rest of Europe it was replaced by versions of the Persian shāh ("king"), which was familiar as an exclamation and became the English words "check" and "chess".[note 3]
The oldest archaeological chess artifacts, ivory pieces, were excavated in ancient Afrasiab, today's Samarkand, in Uzbekistan, central Asia, and date to about 760, with some of them possibly older. The oldest known chess manual was in Arabic and dates to 840–850, written by al-Adli ar-Rumi (800–870), a renowned Arab chess player, titled Kitab ash-shatranj (Book of the chess). This is a lost manuscript, but referenced in later works. The eastern migration of chess, into China and Southeast Asia, has even less documentation than its migration west. The first reference to Chinese chess, called xiàngqí 象棋, appears in a book entitled Xuán guaì lù 玄怪錄("Record of the Mysterious and Strange"), dating to about 800. Alternatively, some contend that chess arose from Chinese chess or one of its predecessors,[15] although this has been contested.[16]
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 both Muslim Iberia and Latin Europe.[17] A Latin poem de scachis dated to the late 10th century has been preserved in Einsiedeln Abbey. A famous 13th-century manuscript covering shatranj, backgammon, and dice is known as the Libro de los juegos.
1200–1700: Origins of the modern game
Around 1200, the rules of shatranj started to be modified in southern Europe, and around 1475, several major changes made the game essentially as it is known today.[17] These modern rules for the basic moves had been adopted in Italy and Spain.[18][19] Pawns gained the option of advancing two squares on their first move, while bishops and queens acquired their modern abilities. The queen replaced the earlier vizier chess piece towards the end of the 10th century and by the 15th century had become the most powerful piece;[20] consequently modern chess was referred to as "Queen's Chess" or "Mad Queen Chess".[21] Castling, derived from the "kings leap" usually in combination with a pawn or rook move to bring the king to safety, was introduced. These new rules quickly spread throughout western Europe.


Writings about the theory of how to play chess began to appear in the 15th century. The 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.[19] Lucena and later masters like Portuguese Pedro Damiano, Italians Giovanni Leonardo Di Bona, Giulio Cesare Polerio and Gioachino Greco, and Spanish bishop Ruy López de Segura developed elements of openings and started to analyze simple endgames.
1700–1873: The Romantic Era in chess
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 Irish master Alexander McDonnell in 1834.[22] Centers of chess activity in this period were coffee houses in major European cities like Café de la Régence in Paris and Simpson's Divan in London.[23][24]
The rules concerning stalemate were finalized in the early 19th century. Also in the 19th century, the convention that White moves first was established (formerly either White or Black could move first). Finally the rules around castling were standardized – variations in the castling rules had persisted in Italy until the late 19th century. The resulting standard game is sometimes referred to as Western chess[25] or international chess,[26] particularly in Asia where other games of the chess family such as xiangqi are prevalent. Since the 19th century, the only rule changes have been technical in nature, for example establishing the correct procedure for claiming a draw by repetition.

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.[27] 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, von der Lasa published his and Bilguer's Handbuch des Schachspiels (Handbook of Chess), the first comprehensive manual of chess theory.
Chess was occasionally criticized in the 19th century as a waste of time.[28][29]
The first modern chess tournament was organized by Howard Staunton, a leading English chess player, and was held in London in 1851. It was won by the German Adolf Anderssen, who was hailed as the leading chess master. His brilliant, energetic attacking style was typical for the time.[30][31] Sparkling games like Anderssen's Immortal Game and Evergreen Game or Morphy's "Opera Game" were regarded as the highest possible summit of the chess art.[32]
The romantic era was characterized by opening gambits (sacrificing pawns or even pieces), daring attacks, and brazen sacrifices. Many elaborate and beautiful but unsound move sequences called "combinations" were played by the masters of the time. The game was played more for art than theory. A profound belief that chess merit resided in the players' genius rather than inherent in the position on the board pervaded chess practice.
Deeper insight into the nature of chess came with the American Paul Morphy, an extraordinary chess prodigy. Morphy won against all important competitors (except Staunton, who refused to play), 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.[33]

1873–1945: Birth of a sport
Prague-born Wilhelm Steinitz beginning in 1873 described how to avoid weaknesses in one's own position and how to create and exploit such weaknesses in the opponent's position.[34] The scientific approach and positional understanding of Steinitz revolutionized the game. Steinitz was the first to break a position down into its components.[35] Before Steinitz, players brought their queen out early, did not completely develop their other pieces, and mounted a quick attack on the opposing king, which either succeeded or failed. The level of defense was poor and players did not form any deep plan.[36] In addition to his theoretical achievements, Steinitz founded an important tradition: his triumph over the leading German master Johannes Zukertort in 1886 is regarded as the first official World Chess Championship. Steinitz lost his crown in 1894 to a much younger player, the German mathematician Emanuel Lasker, who maintained this title for 27 years, the longest tenure of any world champion.[37]
After the end of the 19th century, the number of master tournaments and matches held annually quickly grew. Some sources state that in 1914 the title of chess Grandmaster was first formally conferred by Tsar Nicholas II of Russia to Lasker, Capablanca, Alekhine, Tarrasch, and Marshall, but this is a disputed claim.[note 4] The tradition of awarding such titles was continued by the World Chess Federation (FIDE), founded in 1924 in Paris. In 1927, the Women's World Chess Championship was established; the first to hold the title was Czech-English master Vera Menchik.[38]

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. He briefly lost the title to Dutch player Max Euwe in 1935 and regained it two years later.[39]
Between the world wars, chess was revolutionized by the new theoretical school of so-called hypermodernists like Aron Nimzowitsch and Richard Réti. They advocated controlling the center of the board with distant pieces rather than with pawns, thus inviting opponents to occupy the center with pawns, which become objects of attack.[40]
1945–present: Post-World War II era
After the death of Alekhine, a new World Champion was sought. FIDE, which has controlled the title since then (except for one interruption), ran a tournament of elite players. 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).[41] Botvinnik revolutionized opening theory. Previously Black strove for equality, to neutralize White's first-move advantage. As Black, Botvinnik strove for the initiative from the beginning.[42] In the previous informal system of World Championships, the current 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, and later a series of knockout 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 operated 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 23-year-old 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 player renowned for his defensive and positional skills, held the title for two cycles, 1963–1969. His successor, Boris Spassky from Russia (champion 1969–1972), won games in both positional and sharp tactical style.[43] The next championship, the so-called Match of the Century, saw the first non-Soviet challenger since 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 Karpovwhen FIDE did not meet his demands, and Karpov obtained the title by default.[44] Fischer modernized many aspects of chess, especially by extensively preparing openings.[45]
Karpov defended his title twice against Viktor Korchnoi and dominated the 1970s and early 1980s with a string of tournament successes.[46] Karpov's reign finally ended in 1985 at the hands of Garry Kasparov, another Soviet player from Baku, Azerbaijan. Kasparov and Karpov contested five world title matches between 1984 and 1990; Karpov never won his title back.[47] 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 a series of many games, and 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.[48] The World Chess Championship 2006, in which Kramnik beat the FIDE World Champion Veselin Topalov, reunified the titles and made Kramnik the undisputed World Chess Champion.[49] In September 2007, he lost the title to Viswanathan Anand of India, who won the championship tournamentin Mexico City. Anand defended his title in the revenge match of 2008,[50] 2010 and 2012. In 2013, Magnus Carlsen beat Anand in the 2013 World Chess Championship.[51] He defended his title the following year, again against Anand. Carlsen confirmed his title in 2016 against the Russian Sergey Karjakin [52] and in 2018 against the American Fabiano Caruana,[53] in both occasions by a rapid tiebreaker match after equality in 12 games of classical time control, and is the reigning world champion.