On most forums, users do not have to log in to read existing messages.
Early Internet forums could be described as a web version of an electronic mailing list or newsgroup (such as exist on Usenet); allowing people to post messages and comment on other messages.
One of the first forum sites, and still active today, is Delphi Forums, once called Delphi (online service).
China also has many millions of posts on forums such as Tianya Club.Some of the very first forum systems were the Planet-Forum system, developed in the beginning of the 1970-s, the EIES system, first operational in 1976, and the KOM system, first operational in 1977.Later developments emulated the different newsgroups or individual lists, providing more than one forum, dedicated to a particular topic.with over two million per day on their largest forum, 2channel.
They differ from chat rooms in that messages are often longer than one line of text, and are at least temporarily archived.
Also, depending on the access level of a user or the forum set-up, a posted message might need to be approved by a moderator before it becomes visible.