Queen's Indian Defense, Fianchetto Variation

The Fianchetto Variation is defined by White advancing the g2-pawn to g3. In algebraic notation, 4.g3 means this is White’s fourth move, and Bg2 means the bishop goes to g2. A fianchetto is the plan of moving a flank pawn one square and developing the bishop behind it on a long diagonal. It also makes kingside castling easier, the combined king-and-rook move that carries the king toward the h-side of the board, and usually leaves a stable pawn cover in front of the king.

Black has two main squares for the c8-bishop. With ...Bb7, the bishop pressures e4 and contests the influence of White's g2-bishop. With ...Ba6, it attacks the c4-pawn and may force White to defend it with b3, Qa4, or Qb3. The same variation can therefore become either a central struggle or a very concrete fight over one pawn.

White normally completes Bg2 and O-O, then chooses among e4, d5, or a more patient setup with b3 and Bb2. The cost of g3 is not a serious weakness but the time invested. While White organizes the bishop, Black may pressure c4 or open the center, so move order matters.

The Classical Variation is one specific continuation of this system, marked by ...Bb7, ...Be7, and solid development. Other branches use ...Ba6 and create different problems immediately.