The game of chess is divided into three phases: the opening and endgame. There is a large body of theory regarding how the game should be played in each of these phases the opening and endgame; those who write about chess theory, who are also eminent players, are referred to as "theorists" or "theoreticians". "Opening theory" refers to consensus, broadly represented by current literature on the openings. "Endgame theory" consists of statements regarding specific positions, or positions of a similar type, though there are few universally applicable principles. "Middlegame theory" refers to maxims or principles applicable to the middlegame. The modern trend, however, is to assign paramount importance to analysis of the specific position at hand rather than to general principles; the development of theory in all of these areas has been assisted by the vast literature on the game. In 1913, preeminent chess historian H. J. R. Murray wrote in his 900-page magnum opus A History of Chess that, "The game possesses a literature which in contents exceeds that of all other games combined."
He estimated that at that time the "total number of books on chess, chess magazines, newspapers devoting space to the game exceeds 5,000". In 1949, B. H. Wood estimated that the number had increased to about 20,000. David Hooper and Kenneth Whyld wrote in 1992 that, "Since there has been a steady increase year by year of the number of new chess publications. No one knows how many have been printed..." The world's largest chess library, the John G. White Collection at the Cleveland Public Library, contains over 32,000 chess books and serials, including over 6,000 bound volumes of chess periodicals. Chess players today avail themselves of computer-based sources of information; the earliest printed work on chess theory, whose date can be established with some exactitude, is Repeticion de Amores y Arte de Ajedrez by the Spaniard Luis Ramirez de Lucena, published c. 1497, which included among other things analysis of eleven chess openings. Some of them are known today as the Giuoco Piano, Ruy Lopez, Petroff's Defense, Bishop's Opening, Damiano's Defense, Scandinavian Defense, though Lucena did not use those terms.
The authorship and date of the Göttingen manuscript are not established, its publication date is estimated as being somewhere between 1471 and 1505. It is not known whether Lucena's book was published first; the manuscript includes examples of games with the openings now known as Damiano's Defence, Philidor's Defense, the Giuoco Piano, Petroff's Defense, the Bishop's Opening, the Ruy Lopez, the Ponziani Opening, the Queen's Gambit Accepted, 1.d4 d5 2. Bf4 Bf5, Bird's Opening, the English Opening. Murray observes that it "is no haphazard collection of commencements of games, but is an attempt to deal with the Openings in a systematic way."Fifteen years after Lucena's book, Portuguese apothecary Pedro Damiano published the book Questo libro e da imparare giocare a scachi et de la partiti in Rome. It includes analysis of the Queen's Gambit Accepted, showing what happens when Black tries to keep the gambit pawn with...b5. Damiano's book "was, in contemporary terms, the first bestseller of the modern game."
Harry Golombek writes that it "ran through eight editions in the sixteenth century and continued on into the next century with unflagging popularity." Modern players know Damiano because his name is attached to the weak opening Damiano's Defense, although he condemned rather than endorsed it. These books and ones discuss games played with various openings, opening traps, the best way for both sides to play. Certain sequences of opening moves began to be given names, some of the earliest being Damiano's Defense, the King's Gambit, the Queen's Gambit, the Sicilian Defense. Damiano's book was followed by general treatises on chess play by Ruy López de Segura, Giulio Cesare Polerio, Gioachino Greco, Joseph Bertin, François-André Danican Philidor; the first author to attempt a comprehensive survey of the openings known was Aaron Alexandre in his 1837 work Encyclopedie des echecs. According to Hooper and Whyld, " Jaenisch produced the first openings analysis on modern lines in his Analyse nouvelle des ouvertures."
In 1843, Paul Rudolf von Bilguer published the German Handbuch des Schachspiels, which combined the virtues of Alexandre and Jaenisch's works. The Handbuch, which went through several editions, last being published in several parts in 1912–16, was one of the most important opening references for many decades; the last edition of the Handbuch was edited by Carl Schlechter, who had drawn a match for the World Championship with Emanuel Lasker in 1910. International Master William Hartston called it "a superb work the last to encase the whole of chess knowledge within a single volume."The English master Howard Staunton the world's strongest player from 1843 to 1851, included over 300 pages of analysis of the openings in his 1847 treatise The Chess Player's Handbook. That work became the standard reference work in English-speaking countries, was reprinted 21 times by 1935. However, "as time passed a demand arose for more up-to-date works in English". Wilhelm Steinitz, the first World Champion considered the "father of modern chess," extensively analyzed various double king-pawn openings in his book The Modern Chess Instructor, published in 1889 and 1895.
In 1889, E. Freeborough and the Reverend C. E. Ranken published the first edition of Chess Openings Modern. In 1911, R. C. Griffi
History of chess
The history of chess can be traced back nearly 1500 years, although the earliest origins are uncertain. The earliest predecessor of the game originated in India, before the 6th century AD. From India, the game spread to Persia; when the Arabs conquered Persia, chess was taken up by the Muslim world and subsequently spread to Southern Europe. In Europe, chess evolved into its current form in the 15th century. "Romantic Chess" was the predominant chess playing style from the late 15th century to the 1880s. Chess games of this period emphasised more on quick, tactical maneuvers rather than long-term strategic planning; the Romantic era of play was followed by the Scientific and New Dynamism eras. In the second half of the 19th century, modern chess tournament play began, the first World Chess Championship was held in 1886; the 20th century saw great leaps forward in chess theory and the establishment of the World Chess Federation. Developments in the 21st century include use of computers for analysis, which originated in the 1970s with the first programmed chess games on the market.
Online gaming appeared in the mid-1990s. Chess remains a popular pastime among the general populace to this day. A 2012 survey found that "chess players now make up one of the largest communities in the world: 605 million adults play chess regularly". Chess is played at least once a year by 12% of British people, 15% of Americans, 23% of Germans, 43% of Russians, 70% of Indian people. Precursors to chess originated in India during the Gupta Empire. There, its early form in the 6th century was known as chaturaṅga, which translates as "four divisions": infantry, cavalry and chariotry; these forms are represented by the pieces that would evolve into the modern pawn, knight and rook, respectively. Chess was introduced to Persia from India and became a part of the princely or courtly education of Persian nobility. In Sassanid Persia around 600 the name became chatrang, which subsequently evolved to shatranj, due to Arab Muslims' lack of ch and ng native sounds, the rules were developed further. Players started calling "Shāh!" when attacking the opponent's king, "Shāh Māt!" when the king was attacked and could not escape from attack.
These exclamations persisted in chess. The game was taken up by the Muslim world after the Islamic conquest of Persia, with the pieces keeping their Persian names; the Moors of North Africa rendered Persian "shatranj" as shaṭerej, which gave rise to the Spanish acedrex and ajedrez. Thus, the game came to be called ludus scacchorum or scacci in Latin, scacchi in Italian, escacs in Catalan, échecs in French. From the first chessmen known of in Western Europe being ornamental chess kings brought in as curios by Muslim traders; the Mongols call the game shatar, in Ethiopia it is called senterej, both evidently derived from shatranj. Chess spread directly from the Middle East to Russia, where chess became known as шахматы; 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. Introduced into the Iberian Peninsula by the Moors in the 10th century, it was described in a famous 13th-century manuscript covering shatranj and dice named the Libro de los juegos.
Chess spread throughout the world and many variants of the game soon began taking shape. Buddhist pilgrims, Silk Road traders and others carried it to the Far East where it was transformed and assimilated into a game played on the intersection of the lines of the board rather than within the squares. Chaturanga reached Europe through the Byzantine empire and the expanding Arabian empire. Muslims carried chess to North Africa and Iberia by the 10th century; the game was developed extensively in Europe. By the late 15th century, it had survived a series of prohibitions and Christian Church sanctions to take the shape of the modern game. Modern history saw reliable reference works, competitive chess tournaments, exciting new variants; these factors added to the game's popularity, further bolstered by reliable timing mechanisms, effective rules, charismatic players. The earliest precursor of modern chess is a game called chaturanga, which flourished in India by the 6th century, is the earliest known game to have two essential features found in all chess variations—different pieces having different powers, victory depending on the fate of one piece, the king of modern chess.
The original chess board was mathematically revolutionary, as reported by the infamous Wheat and chessboard problem. A common theory is that India’s development of the board, chess, was due to India’s mathematical enlightenment involving the creation of the number zero. Other game pieces uncovered in archaeological findings are considered as coming from other, distantly related board games, which may have had boards o
University of Cambridge
The University of Cambridge is a collegiate public research university in Cambridge, United Kingdom. Founded in 1209 and granted a Royal Charter by King Henry III in 1231, Cambridge is the second-oldest university in the English-speaking world and the world's fourth-oldest surviving university; the university grew out of an association of scholars who left the University of Oxford after a dispute with the townspeople. The two'ancient universities' share many common features and are referred to jointly as'Oxbridge'; the history and influence of the University of Cambridge has made it one of the most prestigious universities in the world. Cambridge is formed from a variety of institutions which include 31 constituent Colleges and over 100 academic departments organised into six schools. Cambridge University Press, a department of the university, is the world's oldest publishing house and the second-largest university press in the world; the university operates eight cultural and scientific museums, including the Fitzwilliam Museum, as well as a botanic garden.
Cambridge's libraries hold a total of around 15 million books, eight million of which are in Cambridge University Library, a legal deposit library. In the fiscal year ending 31 July 2018, the university had a total income of £1.965 billion, of which £515.5 million was from research grants and contracts. In the financial year ending 2017, the central university and colleges had combined net assets of around £11.8 billion, the largest of any university in the country. However, the true extent of Cambridge's wealth is much higher as many colleges hold their historic main sites, which date as far back as the 13th century, at depreceated valuations. Furthermore, many of the wealthiest colleges do not account for “heritage assets” such as works of art, libraries or artefacts, whose value many college accounts describe as “immaterial”; the university is linked with the development of the high-tech business cluster known as'Silicon Fen'. It is a member of numerous associations and forms part of the'golden triangle' of English universities and Cambridge University Health Partners, an academic health science centre.
As of 2018, Cambridge is the top-ranked university in the United Kingdom according to all major league tables. As of September 2017, Cambridge is ranked the world's second best university by the Times Higher Education World University Rankings, is ranked 3rd worldwide by Academic Ranking of World Universities, 6th by QS, 7th by US News. According to the Times Higher Education ranking, no other institution in the world ranks in the top 10 for as many subjects; the university has educated many notable alumni, including eminent mathematicians, politicians, philosophers, writers and foreign Heads of State. As of March 2019, 118 Nobel Laureates, 11 Fields Medalists, 7 Turing Award winners and 15 British Prime Ministers have been affiliated with Cambridge as students, faculty or research staff. By the late 12th century, the Cambridge area had a scholarly and ecclesiastical reputation, due to monks from the nearby bishopric church of Ely. However, it was an incident at Oxford, most to have led to the establishment of the university: two Oxford scholars were hanged by the town authorities for the death of a woman, without consulting the ecclesiastical authorities, who would take precedence in such a case, but were at that time in conflict with King John.
The University of Oxford went into suspension in protest, most scholars moved to cities such as Paris and Cambridge. After the University of Oxford reformed several years enough scholars remained in Cambridge to form the nucleus of the new university. In order to claim precedence, it is common for Cambridge to trace its founding to the 1231 charter from King Henry III granting it the right to discipline its own members and an exemption from some taxes. A bull in 1233 from Pope Gregory IX gave graduates from Cambridge the right to teach "everywhere in Christendom". After Cambridge was described as a studium generale in a letter from Pope Nicholas IV in 1290, confirmed as such in a bull by Pope John XXII in 1318, it became common for researchers from other European medieval universities to visit Cambridge to study or to give lecture courses; the colleges at the University of Cambridge were an incidental feature of the system. No college is as old as the university itself; the colleges were endowed fellowships of scholars.
There were institutions without endowments, called hostels. The hostels were absorbed by the colleges over the centuries, but they have left some traces, such as the name of Garret Hostel Lane. Hugh Balsham, Bishop of Ely, founded Peterhouse, Cambridge's first college, in 1284. Many colleges were founded during the 14th and 15th centuries, but colleges continued to be established until modern times, although there was a gap of 204 years between the founding of Sidney Sussex in 1596 and that of Downing in 1800; the most established college is Robinson, built in the late 1970s. However, Homerton College only achieved full university college status in March 2010, making it the newest full college. In medieval times, many colleges were founded so that their members would pray for the souls of the founders, were associated with chapels or abbeys; the colleges' focus changed in 1536 with the Dissolution of the Monasteries. King Henry VIII ordered the university to disband its Faculty of Canon Law and to stop teaching "scholastic philosophy".
In response, colleges changed
The queen is the most powerful piece in the game of chess, able to move any number of squares vertically, horizontally or diagonally. Each player starts the game with one queen, placed in the middle of the first rank next to the king; because the queen is the strongest piece, a pawn is promoted to a queen in the vast majority of cases. In the game shatranj, the ancestor of chess that included only male figures, the closest thing to the queen was the ferz, a weak piece only able to move or capture one step diagonally and not at all in any other direction; the modern chess queen gained power in the 15th century. In most languages the piece is known as "queen" or "lady". Asian and Eastern European languages tend to refer to it as minister or advisor. In Polish it is known as the hetman – the name of a major historical military-political office, while in Estonian it is called lipp; the white queen starts on d1, while the black queen starts on d8. With the chessboard oriented the white queen starts on a white square and the black queen starts on a black square—thus the mnemonics "queen gets her color", "queen on color", or "the dress matches the shoes ".
The queen can be moved any number of unoccupied squares in a straight line vertically, horizontally, or diagonally, thus combining the moves of the rook and bishop. The queen captures by occupying the square. Although both players start with one queen each, a pawn can be promoted to any of several types of pieces, including a queen, when the pawn is moved to the player's furthest rank; such a queen created by promotion can be an additional queen, or if the player's queen has been captured, a replacement queen. Pawn promotion to a queen is colloquially called queening, by far the most common type of piece a pawn is promoted to due to the relative power of a queen. Ordinarily, the queen is stronger than a rook and a bishop together, while less strong than two rooks, it is always disadvantageous to exchange the queen for a single piece other than the enemy's queen. The reason that the queen is stronger than a combination of a rook and bishop though they control the same number of squares, is twofold.
First, the queen is more mobile than the rook and the bishop, as the entire power of the queen can be transferred to another location in one move, while transferring the entire firepower of a rook and bishop requires two moves, the bishop always being restricted to squares of one color. Second, the queen is not hampered by the bishop's inability to control squares of the opposite color to the square on which it stands. A factor in favor of the rook and bishop is that they can attack a square twice, while a queen can only do so once. However, experience has shown that this factor is less significant than the points favoring the queen; the queen is strongest when the board is open, when the enemy king is poorly defended, or when there are loose pieces in the enemy camp. Because of her long range and ability to move in multiple directions, the queen is well equipped to execute forks. Compared to other long range pieces, the queen is stronger in closed positions. Beginners develop the queen early in the game, hoping to plunder the enemy position and deliver an early checkmate such as Scholar's mate.
This can expose the harassed queen to attacks by weaker pieces causing the player to lose time. Experienced players prefer to delay developing the queen, instead develop minor pieces in the opening. Early queen attacks are rare in high level chess, but there are some openings with early queen development that are used by high level players. For example, the Scandinavian Defense, which features queen moves by Black on the second and third moves is considered sound, has been played at the world championship level; some less common examples have been observed in high-level games. The Danvers Opening, characterized as a beginner's opening, has been played by the strong American grandmaster Hikaru Nakamura. A queen exchange marks the beginning of the endgame, but there are queen endgames, sometimes queens are exchanged in the opening, long before the endgame. A common goal in the endgame is to promote a pawn to a queen; as the queen has the largest range and mobility and king vs. lone king is an easy win when compared to some other basic mates.
A queen sacrifice is the deliberate sacrifice of a queen in order to gain a more favorable tactical position. The queen was the counsellor or prime minister or vizier, its only move was one square diagonally. Around 1300 CE its move was enhanced to allow it to move two squares with jump onto a same-colored square for its first move, to help the sides to come into contact sooner; the fers changed into the queen over time. The first surviving mention of this piece as a queen or similar was "regina" in the Einsiedeln Poem, written in Latin around 997 and preserved in a monastery at Einsiedeln in Switzerland; some surviving early medieval pieces depict the piece as a queen, the word fers became grammatically feminized in several languages, for example alferza in Spanish and fierce or fierge in French, before it was replaced with names such as reine or dame. The Carmina Burana refer to the queen as femina and coniunx, the name Amazon has sometimes been seen. In Russian it keeps its Persian name of ferz.
A rook is a piece in the strategy board game of chess. The piece was called the tower, marquess and comes; the term castle is considered incorrect, or old-fashioned. Each player starts the game with two rooks, one on each of the corner squares on their own side of the board; the white rooks start on squares a1 and h1, while the black rooks start on a8 and h8. The rook moves vertically, through any number of unoccupied squares; as with captures by other pieces, the rook captures by occupying the square on which the enemy piece sits. The rook participates, with the king, in a special move called castling. In general, rooks are stronger than bishops or knights and are considered greater in value than either of those pieces by nearly two pawns but less valuable than two minor pieces by a pawn. Two rooks are considered to be worth more than a queen. Winning a rook for a bishop or knight is referred to as winning the exchange. Rooks and queens are called heavy pieces or major pieces, as opposed to bishops and knights, the minor pieces.
In the opening, the rooks are blocked in by other pieces and cannot participate in the game. In that position, the rooks support each other, can more move to occupy and control the most favorable files. A common strategic goal is to place a rook on a half-open file. From this position, the rook is unexposed to risk but can exert control on every square on the file. If one file is important, a player might advance one rook on it position the other rook behind – doubling the rooks. A rook on the seventh rank is very powerful, as it threatens the opponent's unadvanced pawns and hems in the enemy king. A rook on the seventh rank is considered sufficient compensation for a pawn. In the diagrammed position from a game between Lev Polugaevsky and Larry Evans, the rook on the seventh rank enables White to draw, despite being a pawn down. Two rooks on the seventh rank are enough to force victory, or at least a draw by perpetual check. Rooks are most powerful towards the end of a game, when they can move unobstructed by pawns and control large numbers of squares.
They are somewhat clumsy at restraining enemy pawns from advancing towards promotion, unless they can occupy the file behind the advancing pawn. As well, a rook best supports a friendly pawn towards promotion from behind it on the same file. In a position with a rook and one or two minor pieces versus two rooks in addition to pawns, other pieces – Lev Alburt advises that the player with the single rook should avoid exchanging the rook for one of his opponent's rooks; the rook is a powerful piece to deliver checkmate. Below are a few examples of rook checkmates. In the medieval shatranj, the rook symbolized a chariot; the Persian word rukh means chariot, the corresponding piece in the original Indian version chaturanga has the name ratha, in modern times it's known as हाथी to hindi speaking players, while east Asian chess games such as xiangqi and shogi have names meaning chariot for the same piece. Persian war chariots were armored, carrying a driver and at least one ranged-weapon bearer, such as an archer.
The sides of the chariot were built to resemble fortified stone work, giving the impression of small, mobile buildings, causing terror on the battlefield. In the West, the rook is universally represented as a crenellated turret. One possible explanation is that when the game was imported to Italy, the Persian rukh became the Italian word rocca, from there spread in the rest of Europe. Another possible explanation is that rooks represent siege towers – the piece is called torre in Italian and Spanish. In Hungarian it is bástya and in Hebrew language it is called צריח. Another possibility is that, as chess moved to Europe long after chariot warfare had been abandoned, a different symbol was needed to represent the rook's concept of feudal power, as such the Europeans adopted a castle to represent a lord and his feudal power, further supported by the name for the rook, the "marquess", named after a nobleperson; the chariot was sometimes represented as a silhouette, a square with two points above representing the horse's heads, which may have been seen to resemble a building with arrowports to the medieval imagination.
An exception is seen in the British Museum's collection of the medieval Lewis chess pieces in which the rooks appear as stern warders or wild-eyed Berserker warriors. Rooks are similar in appearance to small castles, as a result a rook is sometimes called a "castle"; this usage was common in the past but today it is if used in chess literature or among players, except in the expression "castling". In some languages the rook is called a ship: Thai เรือ, Arm
Correspondence chess is chess or variant chess played by various forms of long-distance correspondence through a correspondence chess server, a public internet chess forum, email, or the postal system. Less common methods that have been employed include homing pigeon, it is in contrast to over-the-board chess, where the players sit at a chessboard at the same time, or play at the same time remotely. Correspondence chess allows people or clubs who are geographically distant to play one another without meeting in person; these distant relationships are just one of the many distinct appeals of correspondence chess. The length of a game played by correspondence can vary depending on the method used to transmit moves: a game played via server or by email might last no more than a few days, weeks, or months. Correspondence chess differs from over-the-board play in several respects. While players in OTB chess play one game at a time, correspondence players have several games going at once. Tournament games are played concurrently, some players may have more than one hundred games continuing at the same time.
Time limits in correspondence play are between 30 and 60 days for every 10 moves. This time allows for far deeper calculation. Certain forms of assistance, including books, chess databases and sometimes chess programs, are allowed. Books and databases are universally acceptable, but organizations vary as to whether chess engine use is permitted; the phenomenon of computer assistance has altered the essence of correspondence chess. In addition to profound chess knowledge and analytical discipline, the ability to interpret and guide computer analysis has become important. Given that players with poor chess knowledge can use the strongest computer programs to analyse their games, the gap between the beginner and master player has narrowed in recent years. However, the influence of computer assistance remains controversial in both official and casual play, consensus on the issue of whether to allow computer aid is still lacking. Variant chess games are played on public chess servers or chess forums.
Since the games are a modified form of chess, chess engines may be less helpful, or based on the variant useless. For example, chess games played on an unbounded chessboard, or infinite chess, are untouched by chess-playing software. Correspondence chess tournaments are played under the auspices of an official regulatory body, most the International Correspondence Chess Federation, affiliated with FIDE, the international chess organization. However, the ICCF, which organizes postal and email events, is not the only organization involved in correspondence chess. There are numerous national and regional bodies for postal chess, as well as a number of organisations devoted to organizing email play for free such as the International Email Chess Group, the Free Internet Correspondence Games Server, that runs a world championship cycle, International E-mail Chess Club. However, groups other than the ICCF are not sanctioned by FIDE; the ICCF awards the titles International Master, Senior International Master and International Correspondence Chess Grandmaster—these are equivalent to similar titles awarded by FIDE for over-the-board chess.
The ICCF runs the World Correspondence Chess Championships. Because these events can last a long time, they may overlap: for instance, in February 2005 Joop van Oosterom was declared winner of the eighteenth Championship, though the winner of the seventeenth Championship had not yet been determined. Up until 2004, ICCF correspondence chess was played only via postal mail. For playing by these two forms of transmission, the ICCF developed their own game notation, known as the ICCF numeric notation for the purpose of ICCF correspondence chess. In recent years, the use of powerful chess programs has brought forth new challenges for organizations like the ICCF and the U. S. Chess Federation, necessitating sometimes controversial decisions on the admissibility of such programs in official correspondence play. Moreover, the emergence of the Internet has brought new opportunities for correspondence chess, not all of which are organized by official bodies. Casual correspondence chess includes correspondence play initiated through correspondence chess servers and games played between individuals who meet and play on their own.
Casual correspondence play does not lead to official ratings, though some chess servers will calculate ratings for the players based on results on that server. There are several types of correspondence chess, with server based correspondence chess becoming the most popular form in the world today, with major correspondence servers becoming as large and popular as the online blitz chess servers. Correspondence chess servers are database-driven and carry with them a web-based interface for submitting moves to the database, but they do create the possibility of facilitating any method of transmission, as long as the transmitted moves are audited within the server's database. Server fees vary. Most casual servers use a yearly charging model, whereby players can play as many tournaments or games as they want all year round; some servers offer basic membership with more services available for a fee. More casual servers allow the use of nicknames, have a real-time rating system which adjusts a player's rating after each rated game.
Casual servers t
A bishop is a piece in the board game of chess. Each player begins the game with two bishops. One starts between the king's knight and the king, the other between the queen's knight and the queen; the starting squares are c1 and f1 for White's bishops, c8 and f8 for Black's bishops. The bishop is limited to diagonal movement. Bishops, like all other pieces except the knight, cannot jump over other pieces. A bishop captures by occupying the square; the bishops may be differentiated according to which wing they begin on, i.e. the king's bishop and queen's bishop. As a consequence of its diagonal movement, each bishop always remains on either the white or black squares, so it is common to refer to them as light-squared or dark-squared bishops. A rook is worth about two pawns more than a bishop; the bishop has access to only half of the squares on the board, whereas all squares of the board are accessible to the rook. On an empty board, a rook always attacks fourteen squares, whereas a bishop attacks no more than thirteen and sometimes as few as seven, depending on how near it is to the center.
A king and rook can force checkmate against a lone king, while a king and bishop cannot. In general bishops are equal in strength to knights, but depending on the game situation either may have a distinct advantage. Less experienced players tend to underrate the bishop compared to the knight because the knight can reach all squares and is more adept at forking. More experienced players understand the power of the bishop. Bishops gain in relative strength towards the endgame as more pieces are captured and more open lines become available on which they can operate. A bishop can influence both wings whereas a knight is less capable of doing so. In an open endgame, a pair of bishops is decidedly superior to either a bishop and a knight, or two knights. A player possessing a pair of bishops has a strategic weapon in the form of a long-term threat to trade down to an advantageous endgame. Two bishops and king can force checkmate against a lone king. A bishop and knight can with far greater difficulty than two bishops.
In certain positions a bishop can by itself lose a move. The bishop is capable of pinning a piece, while the knight can do neither. A bishop can in some situations hinder a knight from moving. In these situations, the bishop is said to be "dominating" the knight. On the other hand, in the opening and middlegame a bishop may be hemmed in by pawns of both players, thus be inferior to a knight which can jump over them. A knight check cannot be blocked but a bishop check can. Furthermore, on a crowded board a knight has many tactical opportunities to fork two enemy pieces. A bishop can fork. One such example occurs in the position illustrated, which arises from the Ruy Lopez: 1.e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5.0-0 b5 6. Bb3 Be7?! 7.d4 d6 8.c3 Bg4 9.h3!? Bxf3 10. Qxf3 exd4 11. Qg3 g6 12. Bh6! In the middlegame, a player with only one bishop should place friendly pawns on squares of the color that the bishop cannot move to; this allows the player to control squares of both colors, allows the bishop to move among the pawns, helps fix enemy pawns on squares on which they can be attacked by the bishop.
Such a bishop is referred to as a "good" bishop. Conversely, a bishop, impeded by friendly pawns is referred to as a "bad bishop"; the black light-squared bishop in the French Defense is a notorious example of this concept. However, a "bad" bishop need not always be a weakness if it is outside its own pawn chains. In addition, having a "bad" bishop may be advantageous in an opposite-colored bishops endgame. If the bad bishop is passively placed, it may serve a useful defensive function. Although the black pawns obstruct the white bishop on e2, it has many more attacking possibilities, thus is a good bishop vis-à-vis Black's bad bishop. Black resigned after another ten moves. A bishop may be fianchettoed, for example after moving the g2 pawn to g3 and the bishop on f1 to g2; this can form a strong defense for the castled king on g1 and the bishop can exert strong pressure on the long diagonal. A fianchettoed bishop should not be given up since the resulting holes in the pawn formation may prove to be serious weaknesses if the king has castled on that side of the board.
There are nonetheless some modern opening lines where a fianchettoed bishop is given up for a knight in order to double the opponent's pawns, for example 1.d4 g6 2.c4 Bg7 3. Nc3 c5 4.d5 Bxc3+!? 5.bxc3 f5, a sharp line originated by Roman Dzindzichashvili. Giving up a fianchettoed queen bishop for a knight is less problematic. For example, in Karpov–Browne, San Antonio 1972, after 1.c4 c5 2.b3 Nf6 3. Bb2 g6?!, Karpov gave up his fianchettoed bishop with 4. Bxf6! exf6 5. Nc3, doubling Black's pawns and giving him a hole on d5. An endgame in which each player has only one bishop, one controlling the dark squares and the other the light, will result in a draw if one player has a pawn or sometimes two more than the other; the players tend to gain control of squares of opposite colors, a deadlock results. In endgames with same-colored bish