|The Grünfeld Defence is a chess opening characterised by the moves (in algebraic notation) 1.d4 Nf6 2.c4 g6 3.Nc3 d5.|
It is named after Ernst Grünfeld, the player who first employed the defence in the 1920s]. The defence was later adopted by a number of prominent players, including Vasily Smyslov, Viktor Korchnoi and Bobby Fischer. Garry Kasparov has often used the defence, including in his World Championship matches against Anatoly Karpov in 1986, 1987 and 1990. In more recent years it has been regularly employed by Loek Van Wely, Peter Svidler and Luke McShane among others.
The opening relies on one of the main principles of the hypermodern school, which was coming to the fore in the 1920s - that a large pawn centre could be a liability rather than an asset. This idea is seen most clearly in the Exchange Variation of the defence: 1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.cxd5 Nxd5 5.e4. Now White has an imposing looking centre - and the main continuation 5...Nxc3 bxc3 strengthens it still further - but Black hopes to undermine it with a later ...c5, which, in conjunction with Bg7, should provide good counterplay.
White can adopt a number of approaches other than the Exchange Variation. Among the more popular are 4.Nf3 Bg7 5.Qb3 (known as the Russian System or Smyslov System), and various systems based on Bf4, Bg5 or g3 and Bg2. Systems in which White delays the development of his queen\"s knight to c3 are known as the Neo-Grünfeld Defence.