Help understanding this opening (very common).



hi there!Ba4 is there the other option aside from Bc6,which leads to the Ruy Lopez exchange variation,leading to endgame play where Black's trumps are his two bishops whilw White relies on his better pawn structure to give him a better game.actually, taking the knight Bc6 doesn't win a pawn because Blask replies dc6 ang if white plays Ne5, Qd4! forks the knight and the e-pawn.So Ba4 instead white is planning a complex middlegame with many pieces on the board.study Fischer's games with Ba4 and Bc6 variations to graps the subtleties of the opening.My Sixty Memorable Games...
So why Ba4? Why bring out a bishop and move it back again?