Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bc4/3...Bc5/4. c3/4...Nf6/5. d4/5...exd4/6. b4

= Dubov Gambit =

6. b4
White sacrifices the d4 pawn for quick development and an open d file. White also attacks the Black bishop on c5, forcing it to move. Black can play either 6...Bb6 or 6...Be7.

In contrast to the Evans gambit, White doesn't sacrifice the b pawn. Because of this White has the threat of b5, forcing the knight to move to a5 or e7.

Theory table
'''1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3 Nf6 5. d4 exd4 6. b4'''