Chess Opening Theory/1. e4/1...Nc6/2. d4/2...d5/3. Nc3/3...a6

= Nimzowitsch Defence = It seems that after 3...a6!? Black has given away his pawn for nothing, but the pawn can be regained by 4...Nb4, 5...Nf6 and then Nbxd5. Having a pawn on a6 is constructive because it denies White's bishop the ability to check on b5 which would be bad for black as white has a pawn on d5 for the time being. White's main option here is to accept black's counter gambit with:
 * /4. exd5/

Theory table
.

'1. e4 Nc6 2. d4 d5 3. Nc3 a6'