Chess engine

A chess engine is software that takes a position, searches many possible continuations and reports which moves it judges best, together with a numerical evaluation. Modern engines are much stronger than the best human players, so their suggestions are almost always at least as good as any move a person could find.

An engine usually works in two parts. A search part looks ahead through the tree of moves, and an evaluation part scores the positions at the end of each line. Engines run on ordinary computers and phones, and websites offer built-in analysis boards that use one.

Used well, an engine is a superb checking tool. Play your own game, form your own opinion about a position, and only then ask the engine whether you missed a tactic. Used badly, it becomes a crutch that hands you answers without any understanding. Students who switch the engine on at every move learn little, because the point of training is to build your own judgment. Ask why the engine prefers a move, and try to explain it in words before accepting it. Never use an engine during a rated game, since that is cheating.

It sits close to Engine analysis. Engine analysis is the use of a chess program to search a position and report which moves are strongest, along with a numeric evaluation and the lines it expects both sides to follow.

A neighboring idea is Evaluation bar. The evaluation bar is a vertical or horizontal gauge beside the board that shows, with a bar of black and white, which side the engine thinks is better and by roughly how much.

Also worth reading is Neural network engine. A neural network engine uses a trained neural network to evaluate positions, and NNUE, the efficiently updatable neural network added to Stockfish, combines such an evaluation with fast traditional search.

An engine can tell you what "Chess engine" means for a position, but not which mistakes you keep making; a first lesson with George Li reviews your games and finds those.

Related terms

• Stockfish

  Stockfish is a free, open-source chess engine developed by a worldwide community, widely regarded as one of the strongest engines available and used by many analysis websites and apps.

• Engine analysis

  Engine analysis is the use of a chess program to search a position and report which moves are strongest, along with a numeric evaluation and the lines it expects both sides to follow.

• Evaluation

  An evaluation is a numerical judgment of who stands better in a position, usually given in pawns from White’s point of view, where positive favors White and negative favors Black.

• Neural network engine

  A neural network engine uses a trained neural network to evaluate positions, and NNUE, the efficiently updatable neural network added to Stockfish, combines such an evaluation with fast traditional search.

• Post-game analysis

  Post-game analysis is the discussion or private review held right after a game, in which both players or one player alone retrace the moves and identify the turning points, missed ideas and lessons.

• Blunder check

  A blunder check is a quick test, made by a person before moving or by software afterward, that looks for a move which hangs material, allows a tactic or loses the game outright.

Guides that go further

• How to choose a chess coach

  What to decide first, the questions to ask, what a first lesson should show and the red flags to avoid.

• How much does chess coaching cost?

  Published rates for private, group and subscription chess coaching, with the source and the date of each.

• The first lesson

  A game review, a read on your level and a written study plan from George Li.