Usenet is the biggest message network on the Internet, made up of thousands of message areas (newsgroups) with thousands of messages (articles) posted daily. While access to Usenet via the UUCP and NNTP protocols used to be widely available via ISP's (included free with the cost of Internet access), nowadays, it's less widely available due to abuse, liability concerns and lack of moderation. The SPAM to HAM ratio on Usenet newsgroups has been and continues to be a problem.
Many important historic technical milestones (e.g. the birth of Linux) can be traced to Usenet articles.
Many BBSes have carried USENET newsgroups since the 1980s.