In this paper we describe a model of social and collaborative search based on the use of tags. First we will introduce the issues that drove us to the definition of this model, analyzing different elements characterizing the web 2.0 paradigm and their effect on traditional search and classification systems. Afterwards we will present TAG Vision, a prototype implementation of the model, developed in order to investigate new approaches for information retrieval. Categories and Subject Descriptors H.3.3 [Information Storage and Retrieval]: Information Search and Retrieval