These things can’t be free. There are groups out there that would take up huge ammounts of storage space and have bandwidth usage that would cause most websites to blush. Who is paying for this? Who is maintaing this?
In short, you pay for it, the ISP maintains it.
The ISP’s that I have worked for pay news services for the feeds into the news servers they themselves hosted. The price of hosting the news server and the bandwidth it generated was included in the price of your subscription to the ISP. The actual bandwidth was probably not that huge, as surprisingly few people used the news servers. We would get notices saying they were down from the NOC, and support calls would not come in about it. The most common support call about news would be from someone who had accidentally opened the news reader, and wondered how all of this pornograhic email had gotten into their box, and why they could not delete it. Charter Cable did, at one time limit the bandwitdth and number of connections to their news service. So, the bandwidth has probably gone up a little since then, I suppose.
They aren’t free. Try to log on to any news server but the one your ISP provides and chances are you won’t be able to connect. Google (via the now defunct DejaNews) provides a certain amount of Usenet access, but only of text messages, which are fairly small.
Also, if you check out the larger binary groups, you’ll see that your ISP is probably not providing access to them all, and deletes the messages in them after only a few days. There are various people running news servers with much greater retention and wider group lists, which you can log on to for a fee.
Not free. A typical ISP acct will usually give you about a gig or so of newsgroup access bundled in, which is easily run through if you are DLing large binaries of any kind on a high speed connection. Also, many of the newsgroup servers ISPs use for bundled accts have limited storage capacity on their news servers and thus are often very shallow timewise with limited “retention”, where if you don’t read or DL the file you want within a few days it’s gone, even though it might still be listed in the newsgroup list of available files.
See www.giganews.com (there are a number of others) for the price schedules for typical, high quality newsreader service that offers massive retention (often a month or more) even for binaries.
Good answers but let me back this up to the 50,000 foot level.
Newsgroups aren’t centrally managed. There is a convention to establish newsgroups under the various top-levels (like rec, which requires a vote to establish a new group, or alt which doesn’t). When you send a post to a newsgroup, it is effectively broadcast to all ISPs and the ones that want to carry that newsgroup catch the broadcast and add the post to their store of posts. ISPs pick and choose which ones they want to carry, but most carry a whole bunch (10’s of thousands or more). It’s a bit more complicated but that gives you a model of how it works.
So there is no single place where they are all managed. With that in mind reread the above answers and you’ll have the whole picture.