This document discusses building and sustaining online communities. It covers the key building blocks of community, including communication, membership, influence, fulfilling needs, and shared connections. Examples of online communities like Flickr and Red Cross are provided. The document emphasizes that the basic rules of community are the same online as offline, including the importance of listening, understanding roles, and cultivating a sense of shared experience. It also covers characteristics of social media like participation, openness, conversation, and being connected.