Bulletin Board System...ahhh, good ol' days, when one enjoyed the modem's speaker crackle away as the connection to the "outside" world was initiated!!!

Short Version: the precursor to today's forums, such as our little home right here. BBS'es were often ran on invididual computers that folks would have running in their basements (I did), where the caller's modem would connect to your specific BBS number. Of course, some BBS'es were also hosted on bigger servers, especially as the amount of folks using their modem to connect to the Internet rapidly increased.