MacBinary is a
file format that takes both the
data and
resource forks of a mac file or directory, along with
mac-specific meta-information such as
file and
creator type, and stuffs it into one single data file so that the forked data can be transferred over
networks or onto drives with
file systems that do not understand the concept of a fork.
MacBinary files use the .bin file extension, but you almost never see these files because practically every mac file transfer utility in existence (including FTP-- give a mac-based file server the command quote MACB ENABLE and until you send it quote MACB DISABLE it will encode everything it sends in macbinary) that could possibly use macbinary converts to and from it automatically without even telling you MacBinary was at any point involved. If you need to open a .bin file and you can't figure out how, try Stuffit Expander. I'm not sure how you would go about opening a macbinary file in linux or another unix; i've never had to do it before.
MacBinary is a binary format; there is a format that does the same thing but saves as text called Binhex.