Indian Defense: Normal Variation is a chess opening with the ECO code A50, part of the Indian Defense family. It goes 1. d4 Nf6 2. c4. White opens with 1. d4 (the queen's pawn) and Black answers 1... Nf6. After 3 moves it is Black to move. The lesson on the board explains every move of the line and lets you play it yourself; it is free.
In chessGM's opening book this position continues with 2... c5, 2... g6, 2... e6, 2... e5.
Black answers 1.d4 with 1...Nf6, controlling e4 with a piece instead of a pawn. This flexible move can lead to many systems.
chessGM has a full course for this line: open the Indian Defense: Normal Variation course lesson.