Nimzo-Indian Defense

A popular line of the Indian defense after the queen pawn opening, named after Aron Nimzowitsch. Black's main goal in this opening is the prevention of White's advance of the King pawn, e4.

The opening moves which define the Nimzo-Indian defense are

    1.  d4   Nf6
    2.  c4    e6
    3. Nc3   Bb4
(If necessary, see chess notation for help decoding the moves.)

Black's dark-square bishop is often exchanged for White's queen knight at c3, giving White a doubled pawn on the c-file at the expense of maintaining Black's bishop pair. White may choose to preserve his/her pawn structure with 4. Qc2 (classical variation) which has the disadvantage of removing one of the queen pawn's defenders. Usually White accepts the doubled pawn and will make use of the half-open b-file with his/her queen rook.

The Encyclopedia of Chess Openings denotes this opening by the code ECO E20, with main variations also in the ECO chess codes E3 series.