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The King's Indian Defence is a chess opening that begins 1.d4 Nf6 2.c4 g6 followed by ...Bg7 and ...d6. (3.Nc3 d5 is a Grünfeld Defence rather than a King's Indian.) White usually continues with either 3.Nc3, 3.Nf3 or 3.g3. The King's Indian is a "hypermodern" opening, where Black lets White take the center with the view to later ruining White's "wonderful" position, often by an attack on White's king. It is a risky opening, which has been a favourite of players such as former world champions Garry Kasparov, Bobby Fischer and Tigran Petrosian. Prominent grandmasters John Nunn, Svetozar Gligoric, Wolfgang Uhlmann, and Larry Christiansen have also played this opening frequently.

The main variations of the King's Indian are:

• Classical Variation 3.Nc3 Bg7 4.e4 d6 5.Nf3 0-0 6.Be2 e5
  • Main Line or Mar del Plata variation. 7.0-0 Nc6 8.d5 Ne7 Now white has a wide variety of moves, including 9.b4, 9.Bd2, 9.Ne1, and 9.Nd2, among others. Typically, White will try to attack on the queen-side by preparing c4-c5, while Black will attack on the king-side by moving his king's knight and starting a pawn storm to attack White's king.
  • 7.0-0 Nbd7
  • 7.0-0 exd4 8.Nxd4
  • Exchange Variation 7.dxe5 dxe5 8.Qxd8 Rxd8 White exchanges queens and tries to prove that he has a small advantage in the queenless middlegame. The line is also often played by White players hoping for an early draw, but there is still a lot of play left in the position.
• Sämisch Variation 3.Nc3 Bg7 4.e4 d6 5.f3 This often leads to very sharp play with the players castling on opposite wings and attacking each other's kings, as in the Bagirov-Gufeld game given below.
• Averbakh Variation 3.Nc3 Bg7 4.e4 d6 5.Be2 0-0 6.Bg5
• Four Pawns Attack 3.Nc3 Bg7 4.e4 d6 5. f4 A sharp line in which White tries to overrun Black with his center pawns. Such a strategy entails considerable risk, and analysis constantly shifts back and forth as to its validity. The pawn on f4 prevents Black's usual e5 break, but Black can get counterplay with a c5 break instead. The main line Four Pawns position can also be reached from a Sicilian move order.
• Fianchetto Variation 3.Nf3 Bg7 4.g3 0-0 5.Bg2 d6 6.Nc3 A solid line in which, unlike many variations, White does not have to worry about an attack on his king.

Here is one of the most famous King's Indians, a brilliancy by the late Ukrainian-American grandmaster Eduard Gufeld, who called it his "Mona Lisa":

Bagirov-Gufeld, USSR championship 1973 1.d4 g6 2.c4 Bg7 3.Nc3 d6 4.e4 Nf6 5.f3 0-0 6.Be3 Nc6 7.Nge2 Rb8 8.Qd2 a6 9.Bh6 b5 10.h4 e5 11.Bxg7 Kxg7 12.h5 Kh8 13.Nd5 bxc4 14.hxg6 fxg6 15.Qh6 Nh5 16.g4 Rxb2 17.gxh5 g5 18.Rg1 g4 19.0-0-0 Rxa2 20.Nef4 exf4 21.Nxf4 Rxf4 22.Qxf4 c3 23.Bc4 Ra3 24.fxg4 Nb4 25.Kb1 Be6 26.Bxe6 Nd3 27.Qf7 Qb8+ 28.Bb3 Rxb3+ 29.Kc2 Nb4+ 30.Kxb3 Nd5+ 31.Kc2 Qb2+ 32.Kd3 Qb5+ 0-1