ICCF (International Correspondence Chess Federation) is the official governing body for correspondence chess, a format where games are played over extended periods — days or weeks per move — with players typically consulting databases and engines as part of their analysis. ICCF organizes official rated correspondence tournaments including World Championships, Olympiads, and national team events.

The ICCF server hosts all official games and provides the infrastructure for correspondence play, rating management, and title awards (Correspondence Grandmaster is a distinct title from OTB grandmaster). Players compete asynchronously, submitting moves via the web interface at their own pace within allotted time limits per move.

ICCF membership and entry fees apply for official tournaments; some correspondence play may be free. Correspondence chess played at the highest level features extremely deep theoretical preparation and engine-assisted analysis, representing a distinct chess discipline from over-the-board or online blitz play.