All the strange file formats that data is stored in.
I sort each format in one of the following categories to make it more easy to make sense of them. Listed in order from most to least useful.
Exchange: Format supported by many programs and is often used to move data between programs.
Immediate: Format made for optimal loading directly into the game.
Game: Immediate formats used in existing games.
Obsolete: Old format no longer in common use.
Native: The default way a program save it's data.
What is stored in the file format.