The endgame (or ending) is the final phase of a chess game, following the opening and middlegame. The endgame is characterised by few pieces remaining on the board, increased importance of the king as an active piece, and pawn promotion as a primary objective. Endgame technique is a critical skill that distinguishes strong players. Key endgame concepts include the opposition, zugzwang, the Lucena position, the Philidor position, and corresponding squares.