Reuse, temporal dynamics, interest sharing, and collaboration in social tagging systems

Elizeu Santos-Neto, David Condon, Nazareno Andrade, Adriana Iamnitchi, Matei Ripeanu


User–generated content shapes the dynamics of the World Wide Web. In particular, collaborative tagging represents a simple, yet powerful, feature that enables users to share and collaboratively annotate content such as photos and URLs. This collaborative behavior and the pool of user–generated metadata create opportunities to improve existing systems and to design new mechanisms. However, to realize this potential, it is necessary to first understand the usage characteristics of current systems.

This work addresses this issue by characterizing three tagging systems (CiteULike, Connotea and while focusing on three aspects: i) the patterns of information (tags and items) production; ii) the temporal dynamics of users’ tag vocabularies; and, iii) the social aspects of tagging systems. The analysis of the patterns of information production shows that users publish new content more often than they annotate already existing content in the system. The opposite, however, occurs for tags; the level of tag reuse is much higher. The study of the temporal dynamics of user vocabularies shows that the growth rate of tag vocabularies across the user population over time decreases at early ages, stabilizes, and returns to increase for older users. Moreover, a closer look into the change of vocabulary contents over time shows that despite the fact that tag vocabularies are slowly growing in size with user age, the relative frequency in which each tag is used converges relatively quickly in a users lifetime. Finally, the characterization of social aspects of tagging unveils the relationship between the implicit user ties, as inferred from the similarity between users’ activity, and their explicit social ties, as represented by co–membership in discussion groups or semantic similarity between tag vocabularies.


social tagging; characterization; peer production

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