Interoperability is the ability of a product or system to connect and work with other compatible systems. The development and operation of integrated electronic services for citizens and businesses has been based upon achieving interoperability standards between different information systems developed by various organizations in different countries. Today, the technical interoperability standards emerge from international standardization bodies (IDABC, CEN, UN-CEFACT, etc.) and address public organizations and information systems which provide citizens’ services. Indicatively, EKT develops technical implementation standards for current research information systems (CRIS) according to the model for data interoperability CERIF (Common European Research Information Format). Also, EKT’s repositories operate on common schemas of metadata and follow common interoperability standards which ensure the uniformity of access in the repositories’ digital material and allow the management of diverse types of digital information.