Abstract
Digital health applications (DiGA) are a cog in the machine of a digital health system that must be interoperable like all other communicating applications in order to function smoothly. Interoperability takes place at four levels: functional subject definition of content, semantic and syntactic standardization, security and transport requirements, and organizational aspects.In Germany, a major leap towards a more digital healthcare system has been initiated in recent years, reinforced by the experience gained from the COVID-19 pandemic. Current legislation aims at a uniform definition of standards and processes and thus establishes the required binding framework for an overall concept in digitization. DiGA can communicate with other healthcare systems using the same semantic and syntactic standardizations if the patient so desires. With the possible connection to electronic patient records and the accompanying data donation option, patients can benefit more than once through interoperable DiGA - not only through the direct positive care effect of the digital health application, but also indirectly through data donation, which can contribute to improving the entire healthcare system through appropriate research.