Definitions abour Social Nets
Bookmarklets | MOVABLE TYPE Social Affordance : "properties of an environment that act as socio-contextual facilitators relevant for the learner's social interactions" Kreijins, Kirschner and Jochems, 2002
Social Presence : "the degree of salience of the other person in the interaction and the consequent salience of the interpersonal relationships. (...) Social presence is required to enhance and foster online social interaction, which is the major foundation of social learning" Williams and Christie
The archetypal social affordance device is the coffee machine.