Nimzo-Indian Defence

1.d4 Nf6

2.c4 e6

3.Nc3 Bb4

After 3.Nc3, White threatens to take control over the centre by playing 4.e4. The Nimzo-

Indian, named after the hypermodern player Aron Nimzowitch, is one of the two main ways of

Preventing this (the other way is the direct 3...d5 which leads to the Queen's Gambit Declined).

Black puts a bishop where it pins the White knight, and often intends to trade it off, surrendering the Bishop pair but inflicting White with doubled pawns if needed to recapture with the b-pawn. White can avoid these doubled pawns by playing the queen to c2, but this costs time. On the other hand, Black has not staked out a big claim of the centre yet, and White can get a real space advantage if Black is careless.