The contribution of this work is to apply a semantic approach based on web ontologies to Digital Rights Management. The main result is the development of a copyright ontology. It models the copyright core concepts for creations, rights and the basic kinds of actions that operate on them through their value chain. The set of actions operating on content are the building blocks that combined cope with the complexity of the copyright domain. At the same time, their simplicity guarantees a high level of interoperability and evolvability. The resulting copyright modelling framework is flexible and complete enough to model many copyright scenarios, not just those related to the economic exploitation of content. Additionally, the ontology design and the selection of tools result in a straightforward implementation. Rights are modelled as classes of actions, action patterns are modelled also as classes and concrete actions are modelled as instances. Then, to check if some right or license grants an action is reduced to check for class subsumption and instance classification, which are the main functionalities of Description Logic reasoners.