Chess

Chess is a board game played between two players. It is sometimes called Western chess or international chess to distinguish it from related games such as xiangqi and shogi. The current form of the game emerged in Spain and the rest of Southern Europe during the second half of the 15th century after evolving from chaturanga, a similar but much older game of Indian origin. Today, chess is one of the world's most popular games, played by millions of people worldwide.

Chess is an abstract strategy game and involves no hidden information. It is played on a square chessboard with 64 squares arranged in an eight-by-eight grid. At the start, each player (one controlling the white pieces, the other controlling the black pieces) controls sixteen pieces: one king, one queen, two rooks, two bishops, two knights, and eight pawns. The object of the game is to checkmate the opponent's king, whereby the king is under immediate attack (in "check") and there is no way for it to escape. There are also several ways a game can end in a draw.

Organized chess arose in the 19th century. Chess competition today is governed internationally by FIDE (International Chess Federation). The first universally recognized World Chess Champion, Wilhelm Steinitz, claimed his title in 1886; Magnus Carlsen is the current World Champion. A huge body of chess theory has developed since the game's inception. Aspects of art are found in chess composition, and chess in its turn influenced Western culture and art and has connections with other fields such as mathematics, computer science, and psychology.

One of the goals of early computer scientists was to create a chess-playing machine. In 1997, Deep Blue became the first computer to beat the reigning World Champion in a match when it defeated Garry Kasparov. Today's chess engines are significantly stronger than the best human players, and have deeply influenced the development of chess theory.

Rules

The rules of chess are published by FIDE (Fédération Internationale des Échecs), chess's international governing body, in its Handbook. Rules published by national governing bodies, or by unaffiliated chess organizations, commercial publishers, etc., may differ in some details. FIDE's rules were most recently revised in 2018.

Chess pieces are divided into two different colored sets. While the sets may not be literally white and black (e.g. the light set may be a yellowish or off-white color, the dark set may be brown or red), they are always referred to as "white" and "black". The players of the sets are referred to as White and Black, respectively. Each set consists of 16 pieces: one king, one queen, two rooks, two bishops, two knights, and eight pawns. Chess sets come in a wide variety of styles; for competition, the Staunton pattern is preferred.

The game is played on a square board of eight rows (called ranks) and eight columns (called files). By convention, the 64 squares alternate in color and are referred to as light and dark squares; common colors for chessboards are white and brown, or white and dark green.

The pieces are set out as shown in the diagram and photo. Thus, on White's first rank, from left to right, the pieces are placed in the following order: rook, knight, bishop, queen, king, bishop, knight, rook. On the second rank is placed a row of eight pawns. Black's position mirrors White's, with an equivalent piece on the same file. The board is placed with a light square at the right-hand corner nearest to each player. The correct positions of the king and queen may be remembered by the phrase "queen on her own color" ─ i.e. the white queen begins on a light square and the black queen on a dark square.

In competitive games, the piece colors are allocated to players by the organizers; in informal games, the colors are usually decided randomly, for example by a coin toss, or by one player concealing a white pawn in one hand and a black pawn in the other, and having the opponent choose.

Check and checkmate
When a king is under immediate attack, 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.[1]

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 get it out of check. 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.

Castling

Once per game, each king can make a move known as castling. Castling consists of moving the king two squares toward a rook of the same color on the same rank, and then placing the rook on the square that the king crossed.

Castling is permissible if the following conditions are met:

Neither the king nor the rook has previously moved during the game.
There are no pieces between the king and the rook.
The king is not in check and does not pass through or land on any square attacked by an enemy piece.
Castling is still permitted if the rook is under attack, or if the rook crosses an attacked square.

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 turn immediately following the enemy pawn's two-square advance; otherwise, the right to do so is forfeited. 

Promotion

When a pawn advances to its eighth rank, as 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). If the required piece is not available (e.g. a second queen) an inverted rook is sometimes used as a substitute, but this is not recognized in FIDE sanctioned games.

End of the game

Win

Checkmate: The king is in check and the player has no legal move. (See check and checkmate above)
Resignation: A player may resign, conceding the game to the opponent.[3] Most tournament players consider it good etiquette to resign in a hopeless position.[4][5]
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 were the game to continue.

Draw

Stalemate: If the player to move has no legal move, but is not in check, the position is a stalemate, and the game is drawn.
Dead position: If neither player is able to checkmate the other by any legal sequence of moves, the game is drawn. For example, if only the kings are on the board, all other pieces having been captured, 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. The dead position rule supersedes the previous rule which referred to "insufficient material", extending it to include other positions where checkmate is impossible, such as blocked pawn endings where the pawns cannot be attacked.
Draw by agreement: In tournament chess, 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.
Threefold repetition: 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. The addition of the fivefold repetition rule in 2014 requires the arbiter to intervene immediately and declare the game a draw after five occurrences of the same position, consecutive or otherwise, without requiring a claim by either player. 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. The addition of the seventy-five-move rule in 2014 requires the arbiter to intervene and immediately declare the game drawn after 75 moves without a pawn move or capture, without requiring a claim by either player. 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.
Draw on time: In games with a time control, the game is drawn if a player is out of time and no sequence of legal moves would allow the opponent to checkmate the player.

Time control

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).[1] 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 one 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 competitions. A typical time control is 50 days for every 10 moves.

Notation

Historically, many different notation systems have been used to record chess moves; the standard system today is short-form algebraic notation.[7] In this system, each square is uniquely identified by a set of coordinates, a–h for the files followed by 1–8 for the ranks. The usual format is:

initial of the piece moved – file of destination square – rank of destination square
The pieces are identified by their initials. In English, these are K (king), Q (queen), R (rook), B (bishop), and N (knight; N is used to avoid confusion with king). For example, Qg5 means "queen moves to the g-file, 5th rank" (that is, to the square g5). Different initials may be used for other languages. In chess literature figurine algebraic notation (FAN) is frequently used to aid understanding independent of language.To resolve ambiguities, an additional letter or number is added to indicate the file or rank from which the piece moved (e.g. Ngf3 means "knight from the g-file moves to the square f3"; R1e2 means "rook on the first rank moves to e2"). For pawns, no letter initial is used; so e4 means "pawn moves to the square e4".

If the piece makes a capture, "x" is usually inserted before the destination square. Thus Bxf3 means "bishop captures on f3". When a pawn makes a capture, the file from which the pawn departed is used to identify the pawn making the capture, for example, exd5 (pawn on the e-file captures the piece on d5). Ranks may be omitted if unambiguous, for example, exd (pawn on the e-file captures a piece somewhere on the d-file). A minority of publications use ":" to indicate a capture, and some omit the capture symbol altogether. In its most abbreviated form, exd5 may be rendered simply as ed. An en passant capture may optionally be marked with the notation "e.p."

If a pawn moves to its last rank, achieving promotion, the piece chosen is indicated after the move (for example, e1=Q or e1Q). Castling is indicated by the special notations 0-0 (or O-O) for kingside castling and 0-0-0 (or O-O-O) for queenside castling. A move that places the opponent's king in check usually has the notation "+" added. There are no specific notations for discovered check or double check. Checkmate can be indicated by "#". At the end of the game, "1–0" means White won, "0–1" means Black won, and "½–½" indicates a draw.[1] Chess moves can be annotated with punctuation marks and other symbols. For example: "!" indicates a good move; "!!" an excellent move; "?" a mistake; "??" a blunder; "!?" an interesting move that may not be best; or "?!" a dubious move not easily refuted.For example, one variation of a simple trap known as the Scholar's mate can be recorded:

 1. e4 e5 2. Qh5?! Nc6 3. Bc4 Nf6?? 4. Qxf7#
Variants of algebraic notation include long form algebraic, in which both the departure and destination square are indicated; abbreviated algebraic, in which capture signs, check signs, and ranks of pawn captures may be omitted; and Figurine Algebraic Notation, used in chess publications for universal readability regardless of language.

Portable Game Notation (PGN) is a text-based file format for recording chess games, based on short form English algebraic notation with a small amount of markup. PGN files (suffix .pgn) can be processed by most chess software, as well as being easily readable by humans.

Until about 1980, the majority of English language chess publications used descriptive notation, in which files are identified by the initial letter of the piece that occupies the first rank at the beginning of the game. In descriptive notation, the common opening move 1.e4 is rendered as "1.P-K4" ("pawn to king four"). Another system is ICCF numeric notation, recognized by the International Correspondence Chess Federation though its use is in decline.

In competitive games, players are normally required to keep a score (record of the game). For this purpose, only algebraic notation is recognized in FIDE-sanctioned events; game scores recorded in a different notation system may not be used as evidence in the event of a dispute.

History

Predecessors

The earliest texts referring to the origins of chess date from the beginning of the 7th century. Three are written in Pahlavi (Middle Persian)[42] and one, the Harshacharita, is in Sanskrit.[43] One of these texts, the Chatrang-namak, represents one of the earliest written accounts of chess. The narrator Bozorgmehr explains that Chatrang, the Pahlavi word for chess, was introduced to Persia by 'Dewasarm, a great ruler of India' during the reign of Khosrow I.[44]

The oldest known chess manual was in Arabic and dates to about 840, written by al-Adli ar-Rumi (800–870), a renowned Arab chess player, titled Kitab ash-shatranj (The Book of Chess). This is a lost manuscript, but is referenced in later works. Here also, al-Adli attributes the origins of Persian chess to India, along with the eighth-century collection of fables Kalīla wa-Dimna. By the twentieth century, a substantial consensus[47][48] developed regarding chess's origins in northwest India in the early 7th century.[49][50] More recently, this consensus has been the subject of further scrutiny.[51]

The early forms of chess in India were known as chaturaṅga (Sanskrit: चतुरङ्ग), literally four divisions [of the military] – infantry, cavalry, elephants, and chariotry ─ represented by pieces which would later evolve into the modern pawn, knight, bishop, and rook, respectively. Chaturanga was played on an 8×8 uncheckered board, called ashtāpada.[52] Thence it spread eastward and westward along the Silk Road. The earliest evidence of chess is found in the nearby Sasanian Persia around 600 A.D., where the game came to be known by the name chatrang (Persian: چترنگ). Chatrang was taken up by the Muslim world after the Islamic conquest of Persia (633–51), where it was then named shatranj (Arabic: شطرنج; Persian: شترنج), 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),[53] but in the rest of Europe it was replaced by versions of the Persian shāh ("king"), from which the English words "check" and "chess" descend.[note 3] The word "checkmate" is derived from the Persian shāh māt ("the king is dead").[54]

Xiangqi is the form of chess best-known in China. The eastern migration of chess, into China and Southeast Asia, has even less documentation than its migration west, making it largely conjectured. The word xiàngqí 象棋 was used in China to refer to a game from 569 A.D. at the latest, but it has not been proven if this game was or was not directly related to chess.[55][56] The first reference to Chinese chess appears in a book entitled Xuán guaì lù 玄怪錄 ("Record of the Mysterious and Strange"), dating to about 800. A minority view holds that western chess arose from xiàngqí or one of its predecessors,[57] although this has been contested.[58] Chess historians Jean-Louis Cazaux and Rick Knowlton contend that xiangqi's intrinsic characteristics make it easier to construct an evolutionary path from China to India/Persia than the opposite direction.[59]

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 being older. Remarkably, almost all findings of the oldest pieces come from along the Silk Road, from the former regions of the Tarim Basin (today's Xinjiang in China), Transoxiana, Sogdiana, Bactria, Gandhara, to Iran on one end and to India through Kashmir on the other.[60]

The game reached Western Europe and Russia via at least three routes, the earliest being in the 9th century. By the year 1000, it had spread throughout both the Muslim Iberia and Latin Europe.[61] A Latin poem called de scachis, dated to the late 10th century, has been preserved at the Einsiedeln Abbey.

 1200–1700: Origins of the modern game

The game of chess was then played and known in all European countries. A famous 13th-century Spanish manuscript covering chess, backgammon, and dice is known as the Libro de los juegos, which is the earliest European treatise on chess as well as being the oldest document on European tables games. The rules were fundamentally similar to those of the Arabic shatranj. The differences were mostly in the use of a checkered board instead of a plain monochrome board used by Arabs and the habit of allowing some or all pawns to make an initial double step. In some regions, the Queen, which had replaced the Vizier, and/or the King could also make an initial two-square leap under some conditions.[62]

Around 1200, the rules of shatranj started to be modified in Spain and the rest of Southern Europe, culminating, several major changes later, in the emergence of modern chess practically as it is known today.[63] A major change was the modern piece movement rules, which began to appear in intellectual circles in Valencia, Spain, around 1475,[note 4] which established the foundations and brought it very close to current Chess. These new rules then were quickly adopted in Italy and Southern France before diffusing into the rest of Europe.[66][67] Pawns gained the ability to advance two squares on their first move, while bishops and queens acquired their modern movement powers. The queen replaced the earlier vizier chess piece toward the end of the 10th century and by the 15th century had become the most powerful piece;[68] in light of that, modern chess was often referred to at the time as "Queen's Chess" or "Mad Queen Chess".[69] Castling, derived from the "king's 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 chess theory 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 Ramírez de Lucena was published in Salamanca in 1497.[67] 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 opening theory and started to analyze simple endgames.

1700–1873: The Romantic Era in chess

In the 18th century, the center of European chess life moved from Southern Europe to mainland 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 against Irish master Alexander McDonnell in 1834.[70] 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.[71][72]

At the same time, the intellectual movement of romanticism had had a far-reaching impact on chess, with aesthetics and tactical beauty being held in higher regard than objective soundness and strategic planning. As a result, virtually all games began with the Open Game, and it was considered unsportsmanlike to decline gambits that invited tactical play such as the King's Gambit and the Evans Gambit.[73] This chess philosophy is known as Romantic chess, and a sharp, tactical style consistent with the principles of chess romanticism was predominant until the late 19th century.[74]

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 rules of castling had persisted in Italy until the late 19th century. The resulting standard game is sometimes referred to as Western chess[75] or international chess,[76] particularly in Asia where other games of the chess family such as xiangqi are prevalent. Since the 19th century, the only rule changes, such as the establishment of the correct procedure for claiming a draw by repetition, have been technical in nature.

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.[77] 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.

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.[78][79] Sparkling games like Anderssen's Immortal Game and Evergreen Game or Morphy's "Opera Game" were regarded as the highest possible summit of the art of chess.[80]

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.

1873–1945: Birth of a sport

Prague-born Wilhelm Steinitz laid the foundations for a scientific approach to the game, the art of breaking a position down into components[82] and preparing correct plans.[83] 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. This win marked a stylistic transition at the highest levels of chess from an attacking, tactical style predominant in the Romantic era to a more positional, strategic style introduced to the chess world by Steinitz. 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.[84]

After the end of the 19th century, the number of master tournaments and matches held annually quickly grew. The first Olympiad was held in Paris in 1924, and FIDE was founded initially for the purpose of organizing that event. In 1927, the Women's World Chess Championship was established; the first to hold the title was Czech-English master Vera Menchik.[85]

A prodigy from Cuba, José Raúl Capablanca, known for his skill in endgames, won the World Championship from Lasker in 1921. Capablanca was undefeated in tournament play for eight years, from 1916 to 1924. His successor (1927) was the Russian-French Alexander Alekhine, a strong attacking player who died as the world champion in 1946. Alekhine briefly lost the title to Dutch player Max Euwe in 1935 and regained it two years later.[86]

In the interwar period, 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.

1945–1990: Post-World War II era

After the death of Alekhine, a new World Champion was sought. FIDE, which has controlled the title since then, ran a tournament of elite players. The winner of the 1948 tournament was Russian Mikhail Botvinnik. In 1950 FIDE established a system of titles, conferring the titles of Grandmaster and International Master on 27 players. (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 5])

Botvinnik started an era of Soviet dominance in the chess world, which mainly through the Soviet government's politically inspired efforts to demonstrate intellectual superiority over the West[88][89] stood almost uninterrupted for more than a half-century. Until the dissolution of the Soviet Union, there was only one non-Soviet champion, American Bobby Fischer (champion 1972–1975).[90] Botvinnik also revolutionized opening theory. Previously, Black strove for equality, attempting to neutralize White's first-move advantage. As Black, Botvinnik strove for the initiative from the beginning.[91] 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 through 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 who is widely regarded as one of the most creative players ever,[92] hence his nickname the magician from Riga. 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.[93] The next championship, the so-called Match of the Century, saw the first non-Soviet challenger since World War II, American Bobby Fischer. Fischer defeated his opponents in the Candidates matches by unheard-of margins, and convincingly defeated Spassky for the world championship. The match was followed closely by news media of the day, leading to a surge in popularity for chess; it also held significant political importance at the height of the Cold War, with the match being seen by both sides as a microcosm of the conflict between East and West.[94] In 1975, however, Fischer refused to defend his title against Soviet Anatoly Karpov when he was unable to reach agreement on conditions with FIDE, and Karpov obtained the title by default.[95] Fischer modernized many aspects of chess, especially by extensively preparing openings.[96]

Karpov defended his title twice against Viktor Korchnoi and dominated the 1970s and early 1980s with a string of tournament successes.[97] In the 1984 World Chess Championship, Karpov faced his toughest challenge to date, the young Garry Kasparov from Baku, Soviet Azerbaijan. The match was aborted in controversial circumstances after 5 months and 48 games with Karpov leading by 5 wins to 3, but evidently exhausted; many commentators believed Kasparov, who had won the last two games, would have won the match had it continued. Kasparov won the 1985 rematch. Kasparov and Karpov contested three further closely fought matches in 1986, 1987 and 1990, Kasparov winning them all.[98] Kasparov became the dominant figure of world chess from the mid 1980s until his retirement from competition in 2005.

Beginnings of chess technology
Chess-playing computer programs (later known as chess engines) began to appear in the 1960s. In 1970, the first major computer chess tournament, the North American Computer Chess Championship, was held, followed in 1974 by the first World Computer Chess Championship. In the late 1970s, dedicated home chess computers such as Fidelity Electronics' Chess Challenger became commercially available, as well as software to run on home computers. However, the overall standard of computer chess was low until the 1990s.

The first endgame tablebases, which provided perfect play for relatively simple endgames such as king and rook versus king and bishop, appeared in the late 1970s. This set a precedent to the complete six- and seven-piece tablebases that became available in the 2000s and 2010s respectively.[99]

The first commercial chess database, a collection of chess games searchable by move and position, was introduced by the German company ChessBase in 1987. Databases containing millions of chess games have since had a profound effect on opening theory and other areas of chess research.

Digital chess clocks were invented in 1973, though they did not become commonplace until the 1990s. Digital clocks allow for time controls involving increments and delays.

1990–Present: The rise of computers and online chess
Technology
The Internet enabled a new medium of playing chess, with chess servers allowing users to play other people from different parts of the world in real time. The first such server, known as Internet Chess Server or ICS, was developed at the University of Utah in 1992. ICS formed the basis for the first commercial chess server, the Internet Chess Club, which was launched in 1995, and for other early chess servers such as FICS (Free Internet Chess Server). Since then, many other platforms have appeared, and online chess began to rival over-the-board chess in popularity.[100][101] During the 2020 COVID-19 pandemic, the isolation ensuing from quarantines imposed in many places around the world, combined with the success of the popular Netflix show The Queen's Gambit and other factors such as the popularity of online tournaments (notably PogChamps) and chess Twitch streamers, resulted in a surge of popularity not only for online chess, but for the game of chess in general; this phenomenon has been referred to in the media as the 2020 online chess boom.[102][103]

Computer chess has also seen major advances. By the 1990s, chess engines could consistently defeat most amateurs, and in 1997 Deep Blue defeated World Champion Garry Kasparov in a six-game match, starting an era of computer dominance at the highest level of chess. In the 2010s, engines of superhuman strength became accessible for free on a number of PC and mobile platforms, and free engine analysis became a commonplace feature on internet chess servers. An adverse effect of the easy availability of engine analysis on hand-held devices and personal computers has been the rise of computer cheating, which has grown to be a major concern in both over-the-board and online chess.[104] In 2017, AlphaZero ─ a neural network also capable of playing shogi and Go ─ was introduced. Since then, many chess engines based on neural network evaluation have been written, the best of which have surpassed the traditional "brute-force" engines. AlphaZero also introduced many novel ideas and ways of playing the game, which affected the style of play at the top level.[105]

As endgame tablebases developed, they began to provide perfect play in endgame positions in which the game-theoretical outcome was previously unknown, such as positions with king, queen and pawn against king and queen. In 1991, Lewis Stiller published a tablebase for select six-piece endgames,[106][107] and by 2005, following the publication of Nalimov tablebases, all six-piece endgame positions were solved. In 2012, Lomonosov tablebases were published which solved all seven-piece endgame positions.[108] Use of tablebases enhances the performance of chess engines by providing definitive results in some branches of analysis.

Technological progress made in the 1990s and the 21st century has influenced the way that chess is studied at all levels, as well as the state of chess as a spectator sport.

Previously, preparation at the professional level required an extensive chess library and several subscriptions to publications such as Chess Informant to keep up with opening developments and study opponents' games. Today, preparation at the professional level involves the use of databases containing millions of games, and engines to analyze different opening variations and prepare novelties.[109] A number of online learning resources are also available for players of all levels, such as online courses, tactics trainers, and video lessons.[110]

Since the late 1990s, it has been possible to follow major international chess events online, the players' moves being relayed in real time. Sensory boards have been developed to enable automatic transmission of moves. Chess players will frequently run engines while watching these games, allowing them to quickly identify mistakes by the players and spot tactical opportunities. While in the past the moves have been relayed live, today chess organizers will often impose a half-hour delay as an anti-cheating measure. In the mid-to-late 2010s ─ and especially following the 2020 online boom ─ it became commonplace for supergrandmasters, such as Hikaru Nakamura and Magnus Carlsen, to livestream chess content on platforms such as Twitch.[111][112] Also following the boom, online chess started being viewed as an e-sport, with e-sport teams signing chess players for the first time in 2020.[113]

Growth
Organized chess even for young children has become common. FIDE holds world championships for age levels down to 8 years old. The largest tournaments, in number of players, are those held for children.[114]

The number of grandmasters and other chess professionals has also grown in the modern era. Kenneth Regan and Guy Haworth conducted research involving comparison of move choices by players of different levels and from different periods with the analysis of strong chess engines; they concluded that the increase in the number of grandmasters and higher Elo ratings of the top players reflect an actual increase in the average standard of play, rather than "rating inflation" or "title inflation".

Professional chess
In 1993, Garry Kasparov and Nigel Short broke ties 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 Championships and respective World Champions: the PCA or "classical" champions extending the Steinitzian tradition in which the current champion plays a challenger in a series of games, and the other following FIDE's new format of many players competing in a large knockout tournament to determine the champion. Kasparov lost his PCA title in 2000 to Vladimir Kramnik of Russia.[116] Due to the complicated state of world chess politics and difficulties obtaining commercial sponsorships, Kasparov was never able to challenge for the title again. Despite this, he continued to dominate in top level tournaments and remained the world's highest rated player until his retirement from competitive chess in 2005.

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.[117] In September 2007, he lost the title to Viswanathan Anand of India, who won the championship tournament in Mexico City. Anand defended his title in the revenge match of 2008,[118] 2010 and 2012. In 2013, Magnus Carlsen of Norway beat Anand in the 2013 World Chess Championship. He defended his title 4 times since then and is the reigning world champion.