ASDEX Upgrade is a large experimental device for exploring the concept of magnetic confinement of a high temperature plasma. It is a divertor tokamak of medium size with a fusion reactor relevant cross-section, which is an essential prerequisite for its relevance to the preparation of a future fusion reactor like DEMO. The first wall of ASDEX Upgrade is fully covered with tungsten, a reactor relevant material. ASDEX Upgrade is equipped with a versatile heating and current drive system, including all three day-one systems foreseen for ITER. It has a relatively large total power installed (30 MW, in total) realising ITER relevant power fluxes to the divertor. ASDEX Upgrade also has a large set of diagnostics allowing physics studies with high temporal and spatial resolution. Thus, the aim of the ASDEX Upgrade programme is to prepare the physics base for ITER and DEMO. ASDEX Upgrade is Germany's largest fusion device and one of the leading fusion experiments worldwide. It is operated by the Max Planck Institute for Plasma Physics (IPP) in Garching (close to Munich, Germany) since 1991. The IPP is associated with the European Fusion Programme and the Helmholtz Association of German Research Centres.