In computer science, ontology is the formalization of a field of knowledge to describe complex facts in a machine-readable form. In doing so, a certain structure of objects and their relationships is specified so that computer software can process them. Ontologies are used in computer science mainly for semantic procedures. Here, one is attempting to extract and to model knowledge from an unstructured data stock with the help of machine learning procedures. This way, complex inquiries can for example also be made to a data stock.