This document discusses several key topics related to social networks and online communities:
1. It defines different types of online communities including personal communities, cybercommunities, and how relationships and connections can form within these spaces.
2. It also discusses important aspects that define a community such as membership, influence, needs fulfillment, and emotional connection.
3. The document then examines the concept of a personal community and identifies three defining properties - numbers, constancy, and involvement. It provides examples to illustrate these different properties.