Queen's Indian Defense: Fianchetto Variation, Check Variation, Intermezzo Line

A solid and flexible chess opening for Black, focusing on controlling the light squares and quick development of pieces.

The opening is a popular choice among players who prefer a solid and flexible defense as Black. It is characterized by the early fianchetto of Black's light-squared bishop and the exchange of the dark-squared bishops. This opening aims to control the light squares in the center and on the queenside, while also allowing for quick development of Black's pieces.

In this variation, Black opts for an early check with the dark-squared bishop, forcing White to block with their own bishop. This move is known as the "Intermezzo Line" because it interrupts the normal flow of development. After the exchange of bishops, Black's light-squared bishop is well-placed on the long diagonal, exerting pressure on White's pawn structure.

White's pawn structure is slightly compromised due to the doubled pawns on the b-file, but this can also provide some dynamic possibilities for White, such as opening the c-file for the rook. Black's pawn structure remains solid and flexible, allowing for various pawn breaks in the center and on the queenside.

Both sides have chances for active play, and the position can lead to a rich middlegame with various strategic and tactical possibilities. The opening is suitable for players who enjoy a mix of positional and tactical play, and who are comfortable with slightly unbalanced pawn structures.