Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nf6/3. Nxe5/3...Nxe4/4. Qe2/4...Qe7

Black allow White to take their knight but prepares to pin White's knight.

White will be ahead a pawn if he simply accepts the knight, so 5. Qxe4 is almost universally played. This pins White's knight to their queen, so Black can recover the piece for the cost of the d-pawn. 5...d6 6. d4 dxe5 7. dxe5 Nc6⩲ and Black has partial compensation. White then usually gives back the pawn: if they cling onto it they can find themselves trapped.

The gambit is named for Russian grandmaster Ratmir Kholmov (1925―2006), though he is not known to have played it as Black. The misunderstanding may come from a misattribution of the game Kholmov v Belousov, 1974.^[1][2]

1. e4 e5 2. Nf3 Nf6 3. Nxe5 Nxe4 4. Qe2 Qe7