Threefold repetition — what it means in chess
A draw claim when the same position occurs three times with the same side to move.
A draw claim when the same position occurs three times with the same side to move.
[[board startfen="rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1" caption="Knights out, knights home, twice — and the starting position has now occurred three times with the same player to move. Draw on demand, four moves into the game." pgn="Nf3 Nf6 Ng1 Ng8 Nf3 Nf6 Ng1 Ng8" notes="The starting position: occurrence number one. The rule counts positions, not moves — remember that distinction. White develops. Black mirrors. White retreats. And Black retreats: the starting position stands again, same side to move. Occurrence two. Out once more. Mirrored once more. Home once more. Home — and the starting position has occurred for the third time with White to move. Either player can claim the draw. Nothing was captured, nothing threatened; the position repeated, and that is the entire test."]]
Threefold repetition lets either player claim a draw when the same position occurs three times with the same player to move. The occurrences need not be consecutive, and — the point the demonstration above is built on — the rule counts positions, not moves : it does not matter how the position arose or in what order, only that the identical arrangement stood three times with the same side to play.
"Identical" is stricter than it looks, and the fine print decides real claims. Two positions with every piece on the same square still differ if the castling rights differ (a king that has moved and returned looks the same and is not) or if an en passant capture was available in one and not the other. Repetition claims fail on exactly these details often enough that arbiters check them first.
The Endgame Society glossary defines more than 240 chess terms — rules, notation, tactics, strategy, pawn structures, endgames, and openings — in language a beginner can act on rather than dictionary shorthand.