A chess opening. People who like to simplify early and get a quick free shot on black when playing the Ruy Lopez like the Exchange Variation. I’m sure that there are also Grandmaster type reasons, but for most, its just a way to continue the advantage that white has from being the first one to move. Here is the chess notation.
 
1. e4    e5
2. Nf3   Nc6
3. Bb5   a6
4. Bc6   dc
5. 0-0
There are two reasons why this benefits white. One, it forces black into a poor pawn position with the doubled pawn created by killing the bishop. Secondly, White removes the knight, a very important piece for the opening center struggle, and with the knight removes blacks e5 pawns protector.

Why, as white, you don’t just take the free pawn on the 5th move

 
1. e4    e5
2. Nf3   Nc6
3. Bb5   a6
4. Bc6   dc
5. Nxe5  Qd4!!
With that one move the game is essentially over. White has lost at least two tempo and will lose the pawn if black wishes (Though personally I like Bc5 to rub whites face in the fact that this is now my game). White has no suitable way of defending the knight and must run. Here, on the other side of the coin, is a pretty sharp game where through well paced rational play white comes out on top because of the pawn weakness white causes through the Exchange Variation.

Adorjan-Tringov, Varna, 1972

1. e4    e5
2. Nf3   Nc6
3. Bb5   a6
4. Bc6   dc
5. 0-0   f6
6. d4    Bg4
7. de    Qxd1
8. Rx1   Bf3
9. gf    fe
10. Rd3  Nf6
11. Nd2  b5
12. a4   Bd6
13. Nb3  0-0
14. Na5  c5
15. c4

Chess Openings
The Ruy Lopez
ECO chess codes C6