Queen's Indian Defense, Classical Variation

The Queen’s Indian Defense begins when Black advances the b7-pawn to b6 so the c8-bishop can reach b7. In algebraic notation, B means bishop and O-O means kingside castling, the combined king-and-rook move that carries the king toward the corner. This bishop development is called a fianchetto: a b-pawn or g-pawn moves one square, and the bishop then occupies the opened diagonal behind it. In the Classical Variation, White also prepares a fianchetto with the pawn on g3 and bishop on g2, while Black places the other bishop on e7 and both sides prepare to castle.

The position looks quiet, but the center is still unresolved. White wants to use the c4-pawn and g2-bishop to support e4 or advance d5. Black pressures e4 from b7 and f6 and may answer with ...Ne4, ...c5, or ...d5. A pawn break is an advance intended to open lines or change the pawn structure; ...c5 and ...d5 are Black's main breaks here.

Why it is called Classical

The sequence ...Bb7, ...Be7, and ...O-O represents direct, solid development. Black does not immediately attack c4 with ...Ba6, but completes development and waits for the right moment to challenge the center. White has somewhat more space. Black keeps a flexible structure and may exchange a piece if the lack of space becomes uncomfortable.

The practical key is e4. If White occupies it without making concessions, White controls more of the center. If Black places a knight there or forces favorable exchanges, Black's position becomes freer. The Kasparov Variation changes this discussion by developing Nc3 immediately and allowing ...Bb4.