Data Portability is a concept to protect users from having their data stored in “silos” or “walled gardens” that are incompatible with one another, i.e. closed platforms, thus subjecting them to vendor lock-in and making the creation of data backups or moving accounts between services difficult.
Data portability requires common technical standards to facilitate the transfer from one data controller to another, such as the ability to export user data into a user-accessible local file, thus promoting interoperability, as well as facilitate searchability with sophisticated tools such as grep.
Data portability applies to personal data. It involves access to the personal data without implying data ownership per se. —Wikipedia, “Data portability“