This document discusses interoperability in Europeana, a digital platform for cultural heritage institutions in Europe. It examines Europeana's approach based on the FAIR principles of findable, accessible, interoperable and reusable data. Europeana provides common technical infrastructure and standards to help cultural heritage institutions make their data interoperable online. The document also considers future properties for interoperability, such as intelligent artifacts, self-connecting networks, and multilingual availability.