software designed to help people rendezvous, connect, collaborate, or communicate by use of a computer network

The phrase “social software” refers to how networked applications contribute to building and maintaining a community. Instant messaging, blogs, and text messaging are examples of social software. A community may form online through social software due to a common interest or link. Online communities that are engaged through social software may also meet in the offline world. Generally, social software refers to tools that enable the voluntary formation of communities at the grassroots level.

software, running on an individual's computer or on a website, with which users can create personal profiles, form groups and exchange messages. They can also 'rate' each other and so build reputations.