What is the difference between pseudonymisation and anonymisation?

Pseudonymisation: replaceable via a key, still personal data. Anonymisation: no longer reidentifiable, falls outside GDPR. The line is stricter than most people think.

Try this first

1. 1Pseudonymisation: names to tokens, emails to hashes, BSN to internal ID. The mapping still exists somewhere. GDPR still applies.
2. 2Anonymisation: reidentification is reasonably impossible. All linking removed, including indirect (postcode + age + role).
3. 3Test: can you, with the remaining data plus realistic public info, identify someone? If yes, it is pseudonymous, not anonymous.
4. 4For analytics on production datasets, pseudonymisation often suffices but the key must be secured separately.
5. 5For sharing or public release, only real anonymisation is safe. Often k-anonymity or differential privacy is needed.

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