Correspondence Chess

Unlike rapid chess, a single game of correspondence chess can last anywhere from a few weeks to several months, and sometimes even years. Players traditionally use postal mail or dedicated online servers like the Internet Correspondence Chess Server (ICCF) to submit their moves. This extended timeframe allows for incredibly deep strategic calculation and the use of extensive opening databases.

The rules regarding chess engines vary depending on the specific organization, but traditional correspondence chess platforms associated with the ICCF explicitly permit the use of engine assistance. Players often use powerful software like Stockfish to analyze positions over several days before making a single move. This transforms the game from a test of real-time calculation into a battle of preparation and engine management.

Daily chess on platforms like Chess.com is a modern digital form of correspondence chess where players usually have 1 to 14 days to make a single move. Traditional correspondence chess is strictly governed by the International Correspondence Chess Federation (ICCF) and historically relied on physical postcards. While online daily chess allows for notes and engine use in some leagues, ICCF rules have specific allowances for engine analysis during their official world championship events.

The first official World Correspondence Chess Championship was organized by the ICCF and concluded in 1953, with Cecil Purdy of Australia winning the title. These early championships were conducted entirely via physical mail before the advent of the internet. Purdy's victory helped establish correspondence chess as a highly respected and deeply analytical variant of the traditional game.