Social software enables people to rendezvous, connect or collaborate through computer-mediated communication and to form online communities. from Wikipedia.

Ideally, social software is "bottom-up" software: it supports the desire of individuals to affiliate with others.

Social software supports the notion of individual choice; people affiliate with others out of personal choice.

Social software is dynamic: interaction takes place within the environment that supports it, rather than outside of it.

"The power of Social Software lies in its ability to render apparent the complex, arduous and never ending work of building sociality, of actualizing the virtual, as Deleuze would say." -- Ulises Mejias

How else should we define social software?