Data portability is about you, the user, being able to move and use your data across space (different websites, different devices, different media) and time (archiving, retrieving etc.).
This was one of the incentives behind the development of microformats, and now microformats are a key enabling building block for data portability in various contexts:
- event portability. With hCalendar, it is possible to upload an event from one calendar site to another.