User Modeling (UM) is a cross-disciplinary research topic that can be studied from different perspectives and disciplines, including human-computer interaction, artificial intelligence, psychology and design. This tutorial will focus on the role of user data, knowledge bases and reasoning techniques User Modeling. UM methods aim to create digital representations of users, and then adapt the interface or the content based on these models. The tutorial will first provide an overview of the research in the area, presenting the evolution of User Modeling methods over the years, focusing on the role of data and methods from the social and semantic Web in the creation and enrichment of user models. Examples from most relevant state-of-art work will be presented. Then, we will describe methods and techniques to be used in the User Modeling process to obtain user data, to enrich user data with person-related information as well as data from the Linked Open Data cloud, and to reason about these models. We will give a brief overview on methods for representing user models, how the models are used for providing recommendations and for evaluating these models. Finally, a practical exercise on user model enrichment is presented.