The Big 8 (previously the Big 7) are a group of newsgroup hierarchies established after the Great Renaming, a restructuring of Usenet that took place in 1987. These hierarchies are managed by the Big 8 Management Board. Groups are added through a process of nomination, discussion, and voting.
History
The original seven hierarchies were comp.*, misc.*, news.*, rec.*, sci.*, soc.*, and talk.*. They were open and free for anyone to participate in (except for the moderated newsgroups), though they were subject to a few general rules governing their naming and distribution.
alt.* was not part of the original seven, but created separately as a place with more freedom and fewer rules than the Big 7.
In April 1995, when Usenet traffic grew significantly, humanities.* was introduced, and it and the seven hierarchies created by the Renaming make up today's so-called "Big 8".