SGF file extension - Smart Game Format file
What is sgf file? How to open sgf files?
File type specification:
The SGF file extension is also used for Smart Game Format, a file format that was designed to store game records of board games for two players. It's a text only, tree based format. Therefore games stored in this format can easily be emailed, posted or processed with text-based tools.
The main purposes of SGF are to store records of played games and to provide features for storing annotated and analyzed games (e.g. board markup, variations).