King's gambit

Hard to play in some lines, simple and easy in others. After 3 Nf3 white has taken away the queen check from h4 and can block the bishop check from c5, with tempo. Among the lower rated players who have tried it, Bronstein, Spassky, Kasparov, down to Santasierre. Main reason to play it: it's fun.

#10

Agreed! When I show King's Gambit games to my more novice students I tell them: "Don't try this at home!"

Which, of course, is a bit of a joke, but I do explain that playing the King's Gambit without having studied it is just asking for trouble.

I have just read a small book called "the end of the king's gambit ?" from Iván Salgado López. He has spent time in analyzing main lines and some side lines with the computer. As the king's gambit is a very tactical opening, it is a good idea to get help from chess programs. This opening is useful against players who do not know the theory.
White hopes he will be able to kill his opponent very soon in the game. Unfortunately for him, if black knows the therory, White will have a horrible position.

step 1 : keep the f4 pawn
step 2 : hit the white center

White : - here's my f pawn !
Black : - thanks, I'll keept it. A pawn is a pawn.

A gambit which allows the opponent to keep the material can be considered as refutated.

@Zvneskaia 1. e4 e5 2. f4 exf4 3. Nf3 g5 4. Nc3 d6
5. g3 g4 6. Nh4 f3 7. d4 Bg7 8. Be3 Nc6
9. Qd2 Nf6 10. O-O-O d5 11. e5 Ne4 12. Nxe4 dxe4 here black is clearly up the pawn but white is better and white has no way of taking the pawn back

1. e4 e5 2. f4 exf4 3. Nf3 g5 4. Nc3 d6
5. g3 g4 6. Nh4 f3 7. d4 Bg7 8. Be3 Nc6
9. Qd2 Nf6 10. O-O-O d5 11. exd5 Nxd5 12. Bg5 f6
13. Re1+ Kf7 14. Bc4 fxg5 15. Nxd5 Kf8 16. h3 b5
17. Bb3 Nxd4 18. hxg4 Nxb3+ 19. axb3 Bb7 20. Nf5 Bxd5
21. Qb4+ Kg8 another example also to show how dangerous kings gambit can be

You gave good lines for white. If I consider my high quality KG opening repertoire and the engines, Black has an equal position.
Lines with g5 are the most difficult to play.

1.e4 e5 2.f4 exf4 3.Nf3 g5 4.Nc3 d6 5.g3 g4 6.Nh4 f3 7.d4 Bg7
( 7...Be7 8.Be3 Nc6
( 8...Bxh4 9.gxh4 Qxh4+ 10.Bf2 Qg5 11.Nd5 Nf6 12.Nxc7+ Kd8 13.Nxa8
Nxe4 14.Qc1 Qf6 15.Qe3 Nxf2 16.Qxf2 Re8+ 17.Kd1 Nc6 18.Bb5 Bd7 19.
Re1 Rxe1+ 20.Kxe1 Nxd4 21.Bd3 Kc8 22.Rd1 Kb8 23.Be4 Nc6 24.Qd2
Kxa8 )
9.Qd2 )
8.Bd3
( 8.Be3 Nc6 9.Qd2 Nf6 10.O-O-O d5 11.e5
( 11.exd5 Nxd5 12.Bg5 f6 13.Re1+ Kf7 14.Bc4 fxg5 15.Nxd5 Kf8 16.h3
b5 17.Bb3 Nxd4 18.hxg4 Nxb3+ 19.axb3 Bb7 20.Nf5 Bxd5 21.Qb4+ Kg8 )
11...Ne4 12.Nxe4 dxe4 )
8...Nc6 9.Qd2 Nf6 *

You need to know what you want to do with the opening before you play it. Playing f4 is saying you want to fight for the e5 square in black's camp, but don't want to give up a d-pawn for it. If you know how to play the attacks from black correctly you can get castled and have an open f-file for your rook to attack without having to move it an extra time. If you don't know how to play it, then you may just get stormed on the king side and lose. Of course your opponents has to be careful not to overextend because their pieces might just get separated from the rest of their pieces and just end up doing nothing.

There are so many refutations of the KG. White's hope: Black cannot decide and forfeits.

Equality in a nutshell:

1.e4 e5 2.f4 d5 3.exd5 exf4 =

Its Equality according to engines not humans