Pseudonymization replaces direct identifiers (e.g., name, email) with tokens (pseudonyms) that cannot be traced back to the original individual without a separate mapping key. Art. 4(5) GDPR defines pseudonymization as a technical and organizational measure. Pseudonymized data is still considered personal data because re-identification remains possible with the key. This distinguishes it from anonymized data. Pseudonymization significantly reduces the risk in data breaches, since the exposed data has no direct link to individuals without the key. Store the mapping key separately and under strong protection.