The W3C Media Annotations Working Group has published a Recommendation of Ontology for Media Resources 1.0. The term “Ontology” is used in its broadest possible definition here: a core vocabulary. The intent of this vocabulary is to bridge the different descriptions of media resources, and provide a core set of descriptive properties. This document defines a core set of metadata properties for media resources, along with their mappings to elements from a set of existing metadata formats. The document also presents a Semantic Web compatible implementation of the abstract ontology using RDF/OWL. The document is mostly targeted towards media resources available on the Web, as opposed to media resources that are only accessible in local repositories.