What is the 50 move rule in chess?

The 50-move rule is a regulation in chess that states a player can claim a draw if 50 consecutive moves are made by each player without any pawn movement or any capture. The rule prevents games from going on indefinitely when there is no progress being made towards checkmate.

Here are some key points about the 50-move rule:

1. Definition: A move consists of each player completing one turn. So, 50 consecutive moves refer to 100 individual moves, with both players making their moves alternately.

2. No pawn moves or captures: The rule specifies that if during these 50 moves there is no pawn move or capture, any player (before making their move) can claim a draw due to the 50-move rule.

3. Moves that reset the counter: If a pawn move or capture occurs during the 50-move sequence, the counter for the rule is reset to zero and the count starts again from that moment.

4. Limited exceptions: There are a few exceptions to the 50-move rule. For example, if a checkmate is achieved before the 50-move limit, it takes precedence over the rule. Additionally, if a player is left with only a king in their army, and their opponent cannot checkmate within 50 moves, the game ends in a draw due to insufficient material.

5. Recording moves: It is important to keep a record of moves in order to accurately track the number of moves made without pawn movement or capture. This can be essential for claiming a draw if the 50-move rule is met.

6. Verification by arbiters: In official chess competitions, players may request an arbiter to verify the move count and determine if the 50-move rule applies.

The 50-move rule is designed to avoid situations where a player might attempt to win a game by gradually wearing down their opponent, while being unable to make any decisive progress. It ensures that games conclude within a reasonable timeframe by allowing players to claim a draw when the situation warrants it.