There are a number of very popular social networking sites (SNS) now which allow users to connect and interact with others using a range of tools including instant messaging, email, video, voice chat, file sharing, blogs, wikis, discussion boards and ‘wall’ spaces.
For a short video introduction to social networking, take a look at the video below:
If you’d like some further reading then try:
boyd, d. m., & Ellison, N. B. (2007). Social network sites: Definition, history, and scholarship. Journal of Computer-Mediated Communication, 13(1). http://jcmc.indiana.edu/vol13/issue1/boyd.ellison.html
Selwyn, N. (2007). Screw Blackboard... do it on Facebook! an investigation of students' educational use of Facebook. Paper presented to Poke 1.0 – Facebook social research symposium, November. http://www.scribd.com/doc/513958/Facebook-seminar-paper-Selwyn