Greek Gift and ways of attacking a castled king

Kingside castling is performed to activate the H-rook and to shelter the king behind a wall of pawns, away  from the dangers  of  the  centre  of  the  board.

The king is still vulnerable to attack. One of the most elegant and well-known ways of doing this is via the classical bishop sacrifice, "Greek Gift." Its name alludes to the "Trojan Horse," although in reality, is a Trojan Bishop! (Although another explanation from its title is that it first appeared in Giochino Greco's handbook.