Social network
A social network is a group of people, not larger than about 150 people, who help each other without making it conditional on the exact situation. This is not like a contact network, creative network or power network, which put very specific conditions on help.
The Simple English article on 'social network' has more detail.
Social network analysis
social network analysis may play a formal role in determining what information affects the Consumerium buying signal and may also impact the way some aspects of power structure are interpreted. Some references:
http://www.netform.com/html/information.html
See also the various social network services.