Falcon-AO, a prominent component of Falcon, is an automatic ontology matching system that helps actualize interoperability between (Semantic) Web applications that use different but related ontologies. Recently, it has become a very practical and popular choice for matching Web ontologies expressed by RDF(S) and OWL. Falcon-AO is implemented in Java, and presently, it is an open source project under the Apache 2.0 license.