Interoperability is the ability of different systems, organisations or countries to exchange information and use it meaningfully. For this, participants must interpret shared information correctly, which means using the same standards and processes for an eHealth service.

Interoperability is crucial in the health sector, as this domain is heterogeneous and complex, covering diverse actors ranging from providers to patients, who may be registered in and visit multiple health care institutions. Moreover, healthcare systems often consist of a unique mix of poorly-integrated private and public services.

A healthcare provider may offer only a specific type of service, and thus deal with a subset of patients and their information. This requires well-developed interoperability between institutions, so an overall picture of a patient can be shared.

International healthcare collaboration among EU Member States is often hindered by differences in the eHealth vocabulary used. This results in different interpretations of the same notions and prevents effective cross-border collaboration. Lack of interoperability translates to various problems that citizens face as they attempt to access health services in different institutions and countries. Improved interoperability may effectively improve the continuity and quality of healthcare services experienced in the Eastern partner countries, resulting in a happier and healthier population.