Flag-fall

A chess clock separately measures each player’s remaining time and has an indicator called a flag. On mechanical clocks it was a small marker that dropped when time expired; digital clocks display an equivalent signal. Flag-fall is the moment a player’s allotted time runs out.

Under the rules for games played in person on a physical board, a flag is considered to have fallen when the arbiter, the official who applies tournament rules, observes it or a player makes a valid claim. On an online platform, the system normally detects the timeout automatically.

If the player has not completed the required moves within the allotted time, that player normally loses. The result is instead a draw, a game with no winner, if the opponent cannot give checkmate, meaning an attack on the king with no legal reply, through any possible sequence of legal moves.

Flag-fall describes the clock event, not necessarily the final result by itself. The arbiter or platform must still apply the rule that fits the position and the competition format.