"Supertagger" behavior in building folksonomies

A folksonomy is ostensibly an information structure built up by the "wisdom of the crowds", but is the "crowd" really doing the work? Tagging is in fact a sharply skewed process in which a small minority of users generate an overwhelming majority of the annotations. Using data from the social music site Last.fm as a case study, this paper explores the implications of this tagging imbalance. Partitioning the folksonomy into two halves - one created by the prolific minority and the other by the non-prolific majority of taggers - we examine the large-scale differences in these two sub-folksonomies and the users generating them, and then explore several possible accounts of what might be driving these differences. We find that prolific taggers preferentially annotate content in the long-tail of less popular items, use tags with higher information content, and show greater tagging expertise. These results indicate that "supertaggers" not only tag more than their counterparts, but in quantifiably different ways.