That's the why. That's very roughly what we're aiming for. Now for the How.

Done in two ways:

1 - Presence

Telepresence is a huge topic I wish I had time to go into more here. As it is, I'll just point you towards At The Heart Of It All which summarises different kinds of presence and why presence is good.

In a nutshell, we're interested in the subjective feeling there are other people nearby, and that you all feel like the *same* people are there. That's social copresence. And presence is good because it does things like improve social judgement and improves learning ability and memory.

All you really need for presence is to be able to detect the actions of another person on your computer. It can be anything above seeing whether the other person has turned the application on or not. Realism, little avatars or faces, isn't important.