The aim of provenance research is to break down the origin of objects, this applies to works of art as well as natural history or ethnographica. Starting with the respective object, index cards, inventory book entries or archives can provide clues: how a collection got into the museum, where it came from and who it originally belonged to. The starting point is always the question of whether the objects are legally owned by the museum today, or whether they come from an »illegal context«. Provenance research has established itself as an essential part of museum and collection work, especially in the last few decades. A milestone in this development was the Washington Conference, which in 1998 first laid down how cultural assets confiscated by the National Socialists were to be dealt with. As a result, many museums began examining their own holdings and disclosing problematic provenances.