Pseudonymization is the process of replacing personally identifiable fields within a data record with one or more artificial identifiers or pseudonyms. Commonly used to protect the privacy of personal data, pseudonymization can help support privacy law compliance efforts.

Pseudonymization is often used as an enhancement to data anonymization techniques. However, while anonymized data cannot be traced back to its original source, pseudonymized data can be de-pseudonymized if the key that links the pseudonym to the original data is compromised.

Thus, pseudonymization is not a method of anonymization, but it can help protect privacy when anonymization isn't possible.

As the GDPR has strict requirements for data security and confidentiality, pseudonymization is often used to prevent unauthorized or illegal processing, as well as accidental data loss.