The Nimzo-Indian Defense is a popular chess opening that arises after the moves 1.d4 Nf6 2.c4 e6 3.Nc3 Bb4. It is named after the chess player Aron Nimzowitsch, who was a key figure in the hypermodern movement. This defense allows Black to control the center indirectly while developing pieces harmoniously. In the Nimzo-Indian Defense, Black aims to create imbalances and exert pressure on White's position. By pinning the knight on c3 with the bishop on b4, Black can challenge White's pawn structure and potentially double their pawns. This opening is favored by many players for its strategic depth and flexibility.