Any topic of interest to more than a single individual is the basis of a community. And members of a community can engage in specialized, private conversations, based on the trust of the community. We build trust in various ways. Neighbors get to know each other. Merchants exchange binding contracts.
Researchers meet less frequently, but publish their thinking.
Each of these groups has ways of establishing each other's identity, sharing information securely, conveniently, and regularly, and cooperating in various activities. This point of view can be very illuminating. It means we are not really creating anything fundamentally new with the Internet. We are, however, building fundamentally new technologies for doing many of those things we have always done. Now, any conversation that you might have had over the back yard fence can be had with neighbors on the other side of the world.