The World Wide Web has become the primary source for storing and accessing data. However, its content is marked up in such a way that it is accessible almost exclusively to humans. If we want to enable intelligent services such as information brokers, search agents or information filters to access and process information stored on the WWW, we will soon discover the current technologies will limit us, because the information is hardly structured. In the last years, the Web has evolved from a place in which users could only exchangecontent to the social web in which users have a prominent role by contributingcontent through applications, such as YouTube, Flickr, Delicious and Wikipedia. In this course, we will investigate which tools and technologies are currently available to achieve human-machine content co-creation, and what are their limitations.

More specifically, we will discuss ontologies, a key element of the Semantic Web vision as well, as standards such as RDF and OWL. The role that tagging (i.e. keywords used to describe the resources contributed by users in social media applications) is gaining in the Social Web will also be addressed. We will analyze various algorithms that can be employed to extract structured information from tags leading to a categorization of knowledge that takes users into account. More specifically, we will focus on how the application of Semantic Web technologies to the Social Web is leading towards a Social Semantic Web, in which users, resources and knowledge are closely interlinked.