Board Position
One of the Queen's Pawn Side Defences, the Queen's Indian is Black's major response to 3.Kt-KB3, and as such is regarded as a sister defence to the Nimzo-Indian (where White's 3.Kt-QB3 is met by a 3..B-Kt5 pin).
After setting an Indian KKt, Black pushes 3..P-QKt3(b6) (move 3b, left), preparing to fianchetto his Queen's Bishop in order to strike back at White's K4(e4) square and so prevent an enlarged White pawn centre. Developed by the "hypermodern" school, it was regarded as safe and solid for most of the 20th Century until White's adoption of new ideas in recent years to try and exploit his apparent spatial advantage in better ways.
In the main "classical" line White adopts a king's-side fianchetto (the general best response to a Black Q-side Indian bishop), but the alternative sharp and aggressive Petrosian System has equal popularity.
Begin or Clear or Groups or see move: 1 d4 Nf3 2 c4 e6 3 Nf3 to 3..b6 for:
(Main line:) 4 g3 Bb7 5 Bg2 Be7 6 0-0 0-0 7 Nc3 Ne4 8 Bd2 Bf6 9 Rc1 c5 10 d5 exd5 11 cxd5 Nxd2
(Petrosian V:) 4 a3 Bb7 5 Nc3 d5 6 cxd5 Nxd5 7 e3 Be7 8 Bb5+ c6 9 Bd3 Nxc3 10 bxc3 c5