Anyone is allowed to participate. Some newsgroups have completely free and open discussions and some are moderated by a person who reviews and posts the articles for discussion. Newsgroup discussions may continue over weeks. One does not have to be on line every minute. A chatgroup is a real-time conversation between anyone who is on line at the same time.
People come and go and the topics tend to be social rather than academic.
Newsgroups and chat groups are different from E-mail in that newsgroup and chatgroup postings are sent to one central newsserver, which sends them out to thousands of other servers for anyone to read and discuss. E-mail is sent from one person to another, just like a letter. Newsgroups can be useful for research. If you find a group related to your research topic, you can post questions and get answers. Posting a question to a group may result in a lot of new information.