* hierarchy is a major class of newsgroups in Usenet, containing all newsgroups whose name begins with "comp.
* groups discuss various computer, technology, and programming issues.
Some groups can even offer peer-to-peer technical support.
It often got hijacked by users that weren't aware of the original purpose of the group, believing it was a newsgroup about Windows and Microsoft.
This often led to flame wars between the long time users, who were upset from this situation, and the unaware users.