Source : Free On-Line Dictionary of Computing

FidoNet
     
        A worldwide hobbyist network of personal computers which
        exchanges {e-mail}, discussion groups, and files.  Founded in
        1984 and originally consisting only of {IBM PC}s and
        compatibles, FidoNet now includes such diverse machines as
        {Apple II}s, {Atari}s, {Amiga}s, and {Unix} systems.  Though
        it is much younger than {Usenet}, FidoNet is already (in early
        1991) a significant fraction of {Usenet}'s size at some 8000
        systems.
     
        [{Jargon File}]