Nimzo-Indian Defense, Rubinstein System

The Rubinstein System begins when White's e-pawn advances one square to e3. The move frees the king's bishop, which can develop to e2 or d3. White gives up occupying e4 with that pawn for the moment but gains a stable structure and several ways to develop. It is therefore a broad system, not one mandatory sequence.

The main decision appears if Black exchanges the bishop on b4 for the knight on c3. White can develop the king's knight through e2 so it may recapture on c3 and preserve a clean structure, or accept a b-pawn recapture. The choice changes the balance among speed, space, two bishops, and pawn weaknesses.

Black usually secures the king and attacks the center with the c- or d-pawn. Some branches, including the Hübner Variation, exchange on c3 and try to close the position to restrict White's bishops. Rubinstein names the e3 framework; the specific plans depend on the following moves.