This paper introduces the idea of Web 2.0 to a sociological audience as a key example of a process of cultural digitization that is moving faster than our ability to analyse it. It offers a definition, a schematic overview and a typology of the notion as part of a commitment to a renewal of description in sociology. It provides examples of wikis, folksonomies, mashups and social networking sites and, where possible and by way of illustration, examines instances where sociology and sociologists are featured. The paper then identifies three possible agendas for the development of a viable sociology of Web 2.0: the changing relations between the production and consumption of internet content; the mainstreaming of private information posted to the public domain; and, the emergence of a new rhetoric of 'democratisation'. The paper concludes by discussing some of the ways in which we can engage with these new web applications and go about developing sociological understandings of the new online cultures as they become increasingly significant in the mundane routines of everyday life.