Allowing users to organize content by tagging resources in webbased systems has led to the emergence of the so-called SocialWeb. Tags turned out to be helpful not only for giving recommendations and improving search in social tagging systems but also for enhancing information access by navigating. In this chapter, we will cover much of the pioneer research work that has studied tag-based navigation and visualization. After giving a short overview of the social tagging process and its specifics, we provide an extensive description of the typical user interfaces and visualization techniques characteristic for social tagging systems. As the efficiency of tag-based navigation depends on structuring tagging data, we also provide a review of the state of the art algorithms for tag clustering. Before we conclude, we demonstrate how tag-based navigation can be modeled and discuss the intrinsic navigability of social tagging systems from various theoretic perspectives.