A rook endgame occurs in chess when only a few pieces remain on the board, primarily involving rooks and pawns. In this phase, the ability to coordinate the rook with the king is crucial for both attacking and defending. Players aim to promote their pawns while preventing their opponent from doing the same. Key strategies in rook endgames include controlling open files and using the rook to cut off the opponent's king. Players often seek to create passed pawns, which can advance without being blocked. Understanding these principles can significantly improve endgame performance.