It’s the world’s largest gab fest. If you’re younger than 25, you may never have heard of it. And for many internet users, it’s getting harder to access.

Usenet is a network of tens of thousands of online discussion groups that has been around since 1979. The formal name of these groups is “newsgroup,” designating their original purpose of users delivering news to each other about the subject matter covered by the particular group.

But most groups deliver far more opinion, advice, shared experiences, chitchat, rumors, humor, flirting, and debate than hard news. And, increasingly, over the past 5 years or so, more Usenet content has consisted of pirated films and music, pornography (including child porn), and unrelated advertising (spam).

Comcast, the country’s largest broadband internet service provider (ISP), announced in October that it was discontinuing its Usenet service. Over the summer, Time Warner also announced it was dropping Usenet, while AT&T, Verizon, and Sprint curtailed access to the seedier groups. AOL was the first major ISP to dump Usenet altogether, back in 2005.

The reason officially given typically is the decline in the popularity of Usenet as users have found other ways to communicate online. But pressure from the film and music industry (as a result of the pirated media) and from the government (in particular, the New York state attorney general’s office as a result of the porn) have also played a part. Also, providing Usenet service costs ISPs about $7 per user; ISPs realized this was savings when they no longer offered the service.

Despite its problems, Usenet can still be useful. Whatever your interest may be, you’ll likely find a Usenet group in which people from all over the world are discussing it. Here’s a fairly random sample of a handful of the more interesting or unusual groups.

In soc.history.what-if, people talk about “alternate histories.” Typical discussions are “What if the South won the U.S. Civil War?”; “What if the Holocaust had not happened?”; and such “future history” topics as, “What if terrorists exploded a nuclear bomb in Times Square?”

The group alt.support.dissociation is for the discussion of dissociation, also known as multiple personality disorder or multiplicity. Participants include people afflicted with the disorder and their family and friends, as well as therapists and those simply interested in the phenomenon.

In alt.feminism, women and men talk about discrimination in the workplace, love and marriage, feminist scholarship, and stereotypes. Interestingly, the group welcomes “anti-feminists.” According to the group’s guidelines, “If feminists and anti-feminists can come together to voice their concerns, they may come away with a better understanding of one another.”

If you’ve read a good book lately, rec.arts.books is one place to discuss it. Just don’t reveal how the book ends without including the word “Spoiler” in the subject of your message, unless you want to get browbeaten by others. You’ll likely also receive angry responses if you leave a message such as, “I have a paper due on The Grapes of Wrath. What can people tell me about it?”

The group rec.arts.bodyart is where people talk about tattoos, body piercing, brandings (on humans, not animals), and cuttings. The group offers those “who love to celebrate their bodies through decoration” a sense of community and belonging, according to guidelines.

In misc.kids, people discuss child rearing, ask for advice, and provide encouragement. The discussion can sometimes get heated, says Diane Lin, who wrote the group’s guidelines. Lin asks that participants refrain from name-calling, tantrums, and other hysterics. “We get enough of that from our children,” she says.

Typical discussions in alt.atheism include pretending to be religious to avoid upsetting your family, prayer in schools, discrimination against atheists, and getting rid of unwanted proselytizers.

If you subscribe to an ISP that has dropped Usenet service, you can still access these and the many thousands of other Usenet discussion groups through other means.

The easiest way is by using the web, through Google Groups (groups.google.com). It’s primarily a search and archiving service, however, and participating in Usenet this way is less convenient than going through a specialized Usenet program or the Usenet feature of your email program.

If you want to continue accessing Usenet through a specialized program, you’ll need to subscribe to a third-party newsgroup service provider (NSP). They come in two varieties: pay and free, with the former being more reliable.

Recommended pay NSPs are Giganews (www.giganews.com) and UseNetServer.Com (www.usenetserver.com). For recommendations about free NSPs or those offering free options, check out the Usenet newsgroup alt.free.newsservers, accessible through Google Groups at groups.google.com/group/alt.free.newsservers.