Processing personal data so it can no longer be attributed to a person without separately kept additional information.
Pseudonymization replaces identifying fields with pseudonyms, keeping the key that links them back to individuals separate and secured. The data can still be re-identified with that key, so it remains personal data under the GDPR.
It is a recognized security and data minimization measure that lowers risk while preserving the usefulness of data for analysis or testing.
Related frameworks
KaitoSec