This chapter starts by discussing the challenges in material innovation for manufacturing and the need for multidisciplinary approaches involving actors from many different communities. Interoperability is a key to address these challenges. The new paradigm of materials digitalisation is introduced, and how this can be supported by ontologies, continuing into the requirements that materials digitalisation poses on such ontologies. The Elementary Multiperspective Material Ontology is presented, as well as how this top-level ontology provides the semantic foundation for addressing interoperability and the requirements of materials digitalisation. As an application of these concepts, the key aspects of the flow of data and knowledge, including generation, documentation, management and final exploitation, are presented, and it is shown how they are facilitated by ontologies. Two use cases related to manufacturing are presented together with their challenges and the benefits of approaches based on ontologies and semantic data documentation. The chapter ends by presenting future perspectives and the increasing importance of standardisation and semantic interoperability.