From itproportal.com
Usenet is an early internet technology that allows people to discuss topics and share files on themed bulletin boards known as newsgroups. In many ways, Usenet newsgroups are the technological ancestors of modern discussion platforms like Reddit, Facebook Groups, or website forums.
Originally invented in 1980, Usenet contains a huge collection of millions of posts and binary files across hundreds of thousands of groups, topics, and discussions. Usenet newsgroups still exist, and allow people to search current and historic content, create new discussions, upload and download files, or respond to previous conversations.
But, there’s one major difference between Usenet and more modern discussion forums: if you want to read, contribute to, or download from Usenet newsgroups, you need specialist software, known as a newsgroup reader.