Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...f5/4. d3/4...fxe4

Ruy Lopez, Schliemann Defence

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Common moves:
5. dxe4 - only move

With the bishop already developed on b5, there are no clever gambits in this position - 5. dxe4 is played to recover the pawn.

Wikipedia has related information at Ruy Lopez.