BBS stands for Bulletin Board System. They were all that was the Internet (as far as civilians outside a select few who were granted access to the NSFnet were concerned) before the invention of the World Wide Web. You had to dial their numbers directly using a modem and the numbers were traded amongst friends, listed in BBS magazines or posted on other BBSes. There's a documentary series about it if you're interested.
http://www.youtube.com/watch?v=JnSz-Hb9LQYProfessor Charles Severance of The University of Michigan teaches a fantastic course on the history of the internet and you can take it for free at coursera.org. I've taken the course once already and will problem take it again this coming fall.
https://www.coursera.org/course/insidetheinternetIf you're a visual learner than Coursera might be a great website for you. It offers full college classes in the form of videos and message boards (hey! kinda like Gaia!) but sometimes a little reading is required.