Sharing Vocabularies: Tag Usage in CiteULike

CiteULike is a collaborative tagging web site which lets users enter academic references into a database and describe these references using tags (categorizations of their own choosing). We looked at the tagging behavior of people who were describing four frequently entered references. We found that while people tend to agree on a few select tags, people also tend to use many variants of these tags. This lack of consensus means that the collaborative aspect of tagging is not as strong as may have been suggested in the past.