Editorial - Folksonomies: Why do we need controlled vocabulary?

The Web consists of diverse information collections in terms of the type of content, context, format and quality. However, this diversity, as good as it is, often brings challenges for users in their web information seeking activities. The technologies such as wiki, blog, RSS, and folksonomy that build Web 2.0 present an opportunity to share knowledge and facilitate interactions between users and computers. One of the main challenges of Web 1.0 was that users were not engaged in information organization. Currently folksonomy-based systems (e.g., Del.icio.us) engage users in bookmarking and introducing their favorites. The purpose of this note is to answer the following question: what can a thesaurus do for a folksonomy-based system?