Chess glossary
Plain-English definitions of the chess terms you meet in books, engines and commentary — each with a board diagram and links to practice the idea.
Castling is the only chess move that moves two pieces at once — how it works and when it is legal.
En passant: capturing a pawn that has just advanced two squares — the rule, the deadline and the notation.
Pawn promotion: what the pawn becomes on the last rank, and why underpromotion is sometimes best.
A fork attacks two pieces at once — definition, diagram and links to fork training.
A pin ties a piece to a more valuable target behind it — absolute and relative pins explained.
A skewer forces a valuable piece to move and wins the piece behind it — the reverse of a pin.
A discovered attack opens the line of a second piece — and a discovered check gives two threats in one move.
Check: the king is under attack and the threat must be answered on the very next move.
Checkmate ends the game at once: the king is in check with no legal way out.
Stalemate: no legal moves but no check either — the game is an immediate draw.
Zugzwang: every move makes the position worse, but passing is not allowed.
A gambit invests material in the opening to buy time, lines and the centre.
A fianchetto develops the bishop to g2/b2 where it commands the long diagonal.
Algebraic notation is the standard language for recording chess moves — files, ranks, captures, checks.