Aiff

Who uses 'em - for what with what.

[Statto]

aren't they loss-less audio mac files?

Its like a wav file but on a mac. Like when I use logic and bounce it would come out AIFF. or any other program that gives option for loss less.

WAV and AIF/AIFF are essentially the same thing, all that's different is the way the header information is written. The actual audio held within the file is exactly the same.

yeah this is what I have been taught.. I also heard it can store more metadata inc artwork? Im I just going crazy?

It can certainly store metadata (thats all apple loops are - aiffs with some metadata).
Don't know about graphics though.