Rúy Lopez
This is quite a common variation of the Rúy Lopez - called the old Steinez variation. White has a couple of advantages. That being it weakens blacks pawn structure and means that black will probably castle kingside allowing white to advance the pawns kingside to create a pawn storm. Also it blocks in the dark squared bishop. This comes with disadvantages. It brings in an extra pawn into the centre so black can control the centre and opens up the b file for the rook.
On the other hand, black can push their pawns. Normally, white doesn't take the knight as Bobby Fischer said that bishops should be put at 3.25 points over the knights 3 points. White keeps the pressure on the knight by retreating the bishop. Black then threatens the bishop. This has many disadvantages for white as black gains the tempo, advances the queen-side pawns. The only advantage is getting the bishop to the strong diagonal.
Here are some other variations
Alapin Gambit:
Basque Gambit
Brentano Gambit