Frequently Asked Questions

What is Stockfish?

Stockfish is a strong open-source chess engine used to evaluate positions and suggest best moves. In this app, it analyzes the current game state and returns best lines (principal variations) with scores.

What version of Stockfish does this run?

The engine runs Stockfish 18.

What is a principal variation?

A principal variation is one of Stockfish's best-calculated move sequences from the current position. The first principal variation is the engine's top line, while additional variations are strong alternatives.

What does cp -10 mean in a principal variation?

cp means centipawns, where 100 centipawns is about one pawn of evaluation. A score of cp -10 means the side to move is evaluated as slightly worse by about one tenth of a pawn, which is usually close to equal in practical play.

How do people train with Stockfish?

A common training approach is to first analyze a position on your own, choose a candidate move, then compare it with Stockfish's top lines and evaluations. Players also review their completed games, identify missed tactics or strategic errors, and replay critical positions while checking alternative continuations.

Which notation formats are supported?

The app supports FEN, UCI, and SAN formats for loading and reviewing game state.

What is FEN format and how is it used?

FEN (Forsyth-Edwards Notation) is a compact single-line string that describes a chess position, including piece placement, side to move, castling rights, en passant target, halfmove clock, and fullmove number. It is typically used to load an exact board state for analysis or continuation.

What is the Encyclopedia of Chess Openings (ECO)?

ECO stands for Encyclopedia of Chess Openings, a standard code system for classifying openings from A00 to E99. Broadly, A is flank and irregular openings, B is semi-open games, C is open games and the French Defense, D is closed and semi-closed queen pawn systems, and E is Indian defenses and related queen pawn structures.

What is the difference between SAN and UCI formats?

SAN (Standard Algebraic Notation) is human-friendly move text like Nf3 or Qxe5+, commonly used in books, broadcasts, and PGN game records. UCI uses explicit coordinate moves like g1f3 or d1e2 and is commonly used for engine communication and programmatic processing.

Can I import games from chess.com?

Yes. Enter a chess.com username, load available games, and click a row to load the game position and move history.