comment: A tactical and risky line. White wants to get the queen to c3 or a3, and the game becomes very direct, where the price of forgetting the analysis is very high. More on this shortly.
context: 1. e2e4  1... c7c5  2. g1f3  2... b8c6  3. d2d4  3... c5d4  4. f3d4  4... g8f6  5. b1c3  5... e7e5  6. d4b5  6... d7d6  7. c3d5 Since it was used in some games of the Carlsen-Caruana match, this move has become as important to opening theory as the old main line with 7.Bg5. 7... f6d5  8. e4d5 This is considered better than the alternative 8...Ne7. 8... c6b8 