Nimzo-Indian Defense: Rubinstein System, Hübner Variation

This opening is a solid defense for Black against the Queen's Pawn Opening, focusing on controlling the center and developing pieces efficiently.

The Rubinstein System of the Nimzo-Indian Defense is characterized by Black exchanging the bishop on b4 for the knight on c3, disrupting White's pawn structure. By playing c5, Black aims to challenge White's central pawn on d4 and gain space on the queenside. The move d6 prepares for the development of the light-squared bishop and supports the central pawn on e5. O-O and O-O-O are typical kingside castling options for both players, with Black often choosing the latter to secure the king's safety on the queenside. This opening leads to complex positions where both sides have chances for active play and strategic maneuvering. It is a popular choice among players looking for a solid and flexible defense against 1. d4.