On a personal level, tagging helps individuals organize their stuff (urls, pictures, books, notes). Systems like del.icio.us, LibraryThing, Flickr, YouTube, GMAIL have been adopted by users who add tags to the system in order to find things again. Tags, being short, simple word(s) are easily aggregated across individuals. The curating, and cataloging work done by a few can be leveraged by others in subsequent information discovery.
In this way, tagging implicitly weaves a social system around the individual.It gives users a glimpse of what others on the system are doing; it allows them to "subscribe" to particular individuals, their tags, or their saved items. Individual input can also be aggregated to show social trends.
In this talk I will examine how tagging mediates the personal and the social. At the personal level, I will discuss the benefits of tagging for the individual. I will describe the cognitive underpinnings of tagging, the differences from categorization and how the low cognitive cost makes it popular. At the social level, I will examine the types of social interactions that tagging supports. What are the social characteristics of systems like Flickr and del.icio.us? How are they different from other web-based social systems. I will use James Suroweicki's analysis of the pre-conditions for eliciting "wisdom of crowds" and argue that tagging meets the four conditions more than many other web based social systems.