This document summarizes a lecture on communities. The lecture includes:
1. A recap of a previous brainstorming session
2. A discussion comparing communities and Janus
3. A group work activity where students analyze case studies of communities and write blog posts about them.
4. A mini-presentation and discussion on the differences between networks and communities, and how various social networks online are characterized.
5. An assignment for next class to write two thoughtful questions about blog posts on the topic.