Caro-Kann Defense is a chess opening with the ECO code B15. It goes 1. e4 c6 2. d4 d5 3. Nc3. White opens with 1. e4 (the king's pawn) and Black answers 1... c6. After 5 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 3... dxe4.
Black answers 1.e4 with 1...c6 and then ...d5. It is like the French, but the light-squared bishop can come out first.
chessGM has a full course for this line: open the Caro-Kann Defense course lesson.