Data mining is based on the detection and extraction of knowledge from a database. Web usage mining is a special form of data mining to address behaviour in Web sites. Web usage mining shall be proposed as the central, nonintrusive and objective evaluation technique for the analysis of the usage of Web-based learning and training systems and in particular of the interaction with educational content in these systems. We will introduce and illustrate a number of mining techniques that were developed specifically for the educational context. The behaviour of learners in learning and training technology systems, in particular when a variety of interactive learning and training features is offered, needs to be analysed and evaluated in order to show the effectiveness and to improve, if necessary, the instructional design. We look at techniques to determine the goals of learning sessions, the detailed interaction with content, and the changing of learning behaviour over time.