NIMZO-INDIAN DEFENCE

Board Position
One of the Queen's Pawn Side Defences, it is named after Latvian GM. Aaron Nimzowitsch (1886-1935), who pioneered its successful use in 1914. It is popular with masters and versatile because it enables the Black pieces to contest the centre without being committed to any specific pawn structure.
Being "hypermodern" in strategy it uses an "Indian KKt", but does not set a characteristic fianchetto. Instead, Black's King's Bishop pins White's Q-side knight (move 3b, left) to control White's K4(e4) and so prevent an enlarged White pawn centre. Most lines involve exchanging B-for-Kt - normally a Q-side disadvantage to Black, but here White gets an awkward left wing pawn group.
Full of strategic possibilities, the defence enables White to adopt any of several immediate variations (the Rubinstein being the most popular) while it also allows Black to transpose into the Dutch Defence, the Queen's Indian Defence, the Old Indian Defence and the Queen's Gambit.
Begin or Clear or Groups or see move: 1 d4 Nf3 2 c4 e6 3 Nc3 Bb4 to:
(Rub:) 4 e3 0-0 5 Bd3 d5 6 Nge2 c5 7 cxd5 cxd4 8 exd4 Nxd5 9 0-0 Nc6
(Sam:) 4 a3 Bxc3 5 bxc3 c5 6 f3 d5 7 e3 0-0 8 cxd5 Nxd5 9 Bd2 Nc6 10 Bd3 cxd4 11 cxd4 e5 12 dxe5 Nxe5
(Clas:) 4 Qc2 c5 5 dxc5 0-0 6 Nf3 Na6 7 e3 Nxc5 8 a3 Bxc3+ 9 Qxc3 b6 10 Be2 Ba6 11 b4 Ne4 12 Qb3 d5