KAON (Karlsruhe ontology) is an ontology infrastructure developed by the University of Karlsruhe and the Research Center for Information Technologies in Karlsruhe.Its first incarnation was developed in 2002 and supported an enhanced version of RDF ontologies.Several tools like the graphical ontology editor OIModeler or the KAON Server were based on KAON. There are ontology learning companion tools which take non-annotated natural language text as input: TextToOnto (KAON-based) and Text2Onto (KAON2-based). Text2Onto is based on the Probabilistic Ontology Model (POM).