For an excellent compendium of what early computer discussion networks (or "conferencing systems" as they were often called at the time) were like, as well as a bunch of technical background on the actual data networks and protocols of the time, I'd highly recommend John S. Quarterman's The Matrix, first published in 1989. That is, it predates the World Wide Web, and was only about six years after "The Internet" largely (weasel-word conspicuously noted) replaced "ARPANET" as the designation for the widely-used (amongst university, government, military, and some tech-company) public networking protocol and system based on TCP/IP. Late-breaking news about the effect of computer networks on notable political protests in China are included in the forward.

At the Internet Archive (and apparently from Kahle's own personal collection): <https://archive.org/details/matrixcomputernet00quar/page/n3/...>

I'd begun using Usenet at about the same time as the book was published, and can't personally attest to the information jibal's giving, but will vouch that their account is far more accurate than that to which they're responding.