Chess Opening Theory/1. e4/1...e5/2. f4/2...exf4/3. Nf3/3...g5/4. Bc4/4...g4/5. O-O/5...gxf3

=King's Gambit, Muzio Gambit=

5...gxf3
Black has accepted the Muzio Gambit and must play accurately. White may want to capture the pawn with /6. Qxf3/.