Social software is any software that supports group communications. The dynamics of social software are significantly different from traditional interactions.
Social Software and the Politics of Groups, Clay Shirky, First published March 9, 2003 on the "Networks, Economics, and Culture" mailing list (http://www.shirky.com/writings/group_politics).
... households, and 121 families residing in the town. The population density is 19.9/km² (51.6/mi²). There are 205 housing units at an average density of ...