Sacrifice
A sacrifice is the deliberate act of giving material (pawn or piece) to the opponent to gain other advantages: mating attack, positional advantage, or dynamic-positional gain. Different from blunder where material is lost accidentally, sacrifice has concrete calculation or positional intuition behind it.
Usage and Example
Classic example: bishop sacrifice Bxh7+ followed by Ng5+ and Qh5 (Greek Gift). Thin positional sacrifice: give a pawn to open a file for the rook. Tal was famous for intuitive piece sacrifices without complete calculation.
Grandmaster Tier Context
T3 Competitive Local through T5 Master. Tactical sacrifices appear in T2 puzzles (basic Greek Gift), positional sacrifices appear in T4-T5. Mauricio Flores Rios "Chess Structures: A Grandmaster Guide" covers sacrifice by pawn structure.