With the success of social applications like Flickr, del.icio.us and YouTube, social software has become the focus of several research initiatives. Especially the idea of combining social and semantic aspects has been recently gaining significant attention in the semantic web community. In this paper we research and discuss the properties of metadata in social systems (folksonomies) compared to metadata in semantic systems (ontologies). We then present our idea for creating a link between a folksonomy and an ontology in order to combine the usability and flexibility of folksonomies with the precision of ontologies for a semantic search application. Our approach is motivated by the requirements of the OnTourism project, which has the goal of creating a document repository which benefits from both ontology and folksonomy metadata.