The Fischer Gambit, also called the Tartakower Gambit, is a ploy used to exploit Black's weaknesses on the a2-f7 diagonal. If Black accepts playing 3...Bxb4, the most common continuation will be 4.Bc4.
Your whole game plan will revolve around this diagonal and Black will struggle to castle. Of course he can decline. 3...d5, 3...Ne7 and 3...c6 have all been played regularly.
It seems very likely that the great Philidor would have loved playing this opening with either color. In most lines the battle rages as the two pawn shells go at it with the pieces waiting behind for a chance to eventually infiltrate. This gambit can build a great awareness of how to play with pawns.