Now used mostly as a synonym for newsgroups and seen as yet another internet feature, the term originally covered both news and email, and usenet developed parallel to and partly independent of internet. In the seventies and eighties, a lot of mail and news found their way through mundane telephone lines, using Unix' native networking abilities.
Basically, usenet is a strictly text-only thing. But soon ways were found to encode binaries as text; first UUencoding and now yEncoding. So binary newsgroups were born.
There are quite a lot of them, and since they create heavy traffic, many news servers host only a few or none at all. So the real afficionados often subscribe to specialiced news servers, which can be quite expensive, up to $100/month.
While most browsers and email programs are capable of reading and posting to newsgroups, it can be a good idea to have a specialized program, especially if you are interested in binaries.
This is a new standard of binary encoding for newsgroups. In those groups that deal with large files it is already predominantely used, so it might be a good idea to have a newsreader that supports it.
Many newsgroups maintain a document called FAQ: Frequently Asked Questions. It is posted regularily - the idea is that it should be on the servers continually - and often uploaded to a website, too. First some archives:
And here some individually posted FAQs, strictly in alphabetic order. These are not my favorite newsgroups, or anything such. Some time ago I searched for newsgroup FAQs posted outside the abovementioned archives, gravitating but not restricting myself to those that were in a somewhat pleasant HTML format. So thematically, the section is completely arbitrary. I check them from time to time and update or remove broken links, but will probably not be adding any. So expect this list to shrink.
This is the largest hierarchy. Newsgroups to all kinds of topics can be found here. It was created during the great renaming, and contains many groups that would previously have been found in the rec.* hierarchy, for example all those related to computer games, or the soc.* hierarchy.
I mostly ignore the comp.* hierarchy with its many specialized newsgroups, since these FAQs are usually about technical issues, not about the dos and don'ts of newsgroup posting.
This is a kind of meta-hierarchy, containing topics about Usenet itself.
Arts, games, sports, food, gardening, and similar topics have their home here.
Mainly nations, regions, religions, and lifestyles have their place here. Alternative lifestyles are often found in the alt.* hierarchy (see above), as are most topics related to sexuality.
talk.* is one of the old hierarchies. Idon't know much about it, and found only this one FAQ.