This paper analyzes the tagging patterns exhibited by users of del.icio.us, to assess how collaborative tagging supports and enhances traditional ways of classifying and indexing documents. Using frequency data and co-word analysis matrices analyzed by multi-dimensional scaling, the authors discovered that tagging practices to some extent work in ways that are continuous with conventional indexing. Small numbers of tags tend to emerge by unspoken consensus, and inconsistencies follow several predictable patterns that can easily be anticipated. However, the tags also indicated intriguing practices relating to time and task which suggest the presence of an extra dimension in classification and organization, a dimension which conventional systems are unable to facilitate.

"Philosophical relativism appears to be the underlying philosophy behind folksonomies. Because of those underpinnings, it is possible to jettison the limitations of a traditional classification statement such as "A is not B". In a folksonomy system, "A is relative to B", because each item's index terms will depend on the individual user and the tags he or she decides to use. A philosophy of relativism allows folksonomy to draw on many users with various perceptions to classify a document instead of relying on one individual cataloger to set the index terms for that item. Thus, classification terms become relative to each user."

A relatively short article on tagging systems, and their popularity.