What is data portability? Simply stated, data portability is the means of ensuring that data within a service is not prevented from extraction and reuse independently or with another service.
In practice, a simple example might be unstructured data such as a photo service allowing one to download all the individual’s photos associated with that service. In effect, an individual can extract what was placed into a service.
For a complex example, imagine a social photo sharing service. In this more complex example, data portability might mean access to similarly unstructured data such as the complete timeline of various photo artifacts in a raw format, social updates or comments relating to those artifacts, and related records relating to the metadata for those artifacts in a variety of open formats (json, html, tgz, zip, or similar archives) that are structured so as to be both accessible and more accessed independently with generally available software or for import to another service.