Forsyth-Edwards notation

The Forsyth Edwards Notation (FEN) or in its extended form (X-FEN) is a short notation, which can be used to write down any board position in chess.

FEN is based on a system developed by the Scottish newspaper journalist David Forsyth. This system became popular in the 19th century. It was extended by Steven J. Edwards to support computer use. FEN is an integral part of Portable Game Notation, where it is used to enter starting positions that differ from the starting position of the game.