One person will post an opinion about something and then later that day someone else will read it and respond to it. Because it doesn't take place in real time, people tend to put more thought into their posts and the topics become more of a discussion. There are newsgroups on just about any subject that interests you. Don't worry if you don't think you could come up with an opinion to post. There are only a small percentage of people frequenting newsgroups who actually post.
Most people are just there because they enjoy reading other people's comments.
The purpose of this discussion is tell you how to set up your browser so you can receive newsgroups. There are a lot of people who are missing out on newsgroups because they've never taken the time to figure out how to connect to them. There is no additional cost involved in being connected to newsgroups. It is included in your ISP connection cost. There are approximately 50,000 newsgroups and no ISP will provide access to them all.