What is Classical Bishop Sacrifice?

The classical bishop sacrifice (also known as the Greek Gift sacrifice) is a tactical pattern in which a bishop is sacrificed on h7 (or h2 for Black), drawing the opponent's king onto the open h-file where it is exposed to a mating attack. The sacrifice is typically followed by Ng5+ and Qh5 (or ...Ng4+ and ...Qh4), with devastating threats. See Greek Gift sacrifice.