Postal chess

Postal chess is a form of correspondence chess: the opponents do not sit at the same board, but send moves over distance and normally have far more thinking time than in a live game. What makes it postal is the transmission method. Traditionally, each move travels on a postcard or in a letter.

The normal rules of chess still govern the game, but extra rules are needed to record and transmit moves. In postal events run by the International Correspondence Chess Federation (ICCF), each move is numbered and written either in numeric notation, a system that identifies each square with two digits, or in another notation agreed by both players. The reply also records the date on which the opponent's latest move was received and the expected posting date of the response. A legal move that has already been posted cannot be withdrawn merely because the player changes their mind.

The way moves are sent should not be confused with the rules on outside assistance. In ICCF events, players may consult public sources, including books, databases, and chess-analysis programs, although they must decide their own moves. Other organizers may set different conditions.