The Queen's Indian Defense for Black

1.d4 Nf6 2.c4 e6 3.Nf3 b6

The Queen's Indian is one of the most solid answers to 1.d4 when White avoids the Nimzo-Indian with 3.Nf3. With 3...b6 Black prepares the fianchetto: from b7 the bishop controls the square e4 and the long diagonal; often it also goes to a6 and attacks c4. Black fights for the centre not with pawns but with pieces – d5 or c5 come later. Against the main road 4.g3 the course plays 4...Ba6, against the Petrosian Variation 4.a3 the set-up with 4...Bb7 and 5...d5. Stockfish sees White only slightly ahead in all lines, by one or two tenths – a very good value for Black. The course rests on 18,668 games. White's other roads are 4.Nc3 and 4.e3.

The bishop on b7 controls e4 – as long as White cannot play e4, Black has enough in the centre.
Against White's fianchetto, Ba6 attacks the pawn on c4 and forces White into b3, Qa4, Nbd2 or Qb3.
After b3, Bb4 uses the weakness on c3: White's bishop has to go to d2 and stands in the way there.
The levers c5 and d5 come once the pieces are out – often with c6 and d5 as a firm centre.
If White gives the bishop on f6, recapture with a piece – taking back with the g-pawn tears open the king in several lines.