1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 - See Nimzo-Indian.
4.e3 - Rubinstein Variation. White solidifies the center.
White's plans: Play Bd3, Nge2, O-O. Slow development with a solid center.
Black's plans: Play ...O-O, ...d5, ...c5. Target the slightly passive bishop.
Watch the moves to understand the opening sequence. Use the controls to replay or auto-play the variation.