IFF stands for Interchange File Format. It was created by Electronic Arts in the mid-80s for the Commodore Amiga. IFF is an extendable file format that you can use for almost everything, and IMHO is the greatest format ever, but it has never been really successfull on other platforms. On PCs some programs (like Deluxe Paint) saved images as LBMs, which is basically an IFF file with an image inside.