A chess engine is a computer program designed to analyze and play chess. It evaluates positions on the chessboard using complex algorithms and vast databases of chess knowledge. Chess engines can calculate millions of possible moves per second, helping players improve their skills or providing challenging opponents. These engines are often used in conjunction with graphical user interfaces, allowing users to interact with them easily. Popular chess engines include Stockfish and AlphaZero, which have significantly advanced the understanding of chess strategies. They are also utilized in online platforms and tournaments to assist players and analyze games.