Usenet is a worldwide distributed discussion system. It was developed from the general-purpose UUCP dial-up network architecture. Tom Truscott and Jim Ellis conceived the idea in 1979, and it was established in 1980. Users read and post messages (called articles or posts, and collectively termed news) to one or more categories, known as newsgroups. Usenet resembles a bulletin board system (BBS) in many respects and is the precursor to Internet forums that are widely used today. Usenet can be superficially regarded as a hybrid between email and web forums. Discussions are threaded, as with web forums and BBSs, though posts are stored on the server sequentially.