Communities and the Web

What is a social network? How does an online community differ from a real world community? See also: Anne Hornsby, 'Surfing the net for community: a Durkheimian analysis of electronic gatherings' ch.3 in Peter Kivisto (ed.) Illuminating Social Life (3rd ed 2005). Libr ref HM51KIV. Graham Crow and Catherine Maclean, 'Community' in Geoff Payne (ed.) Social Divisions (2nd ed. 2006) HM821PAY.