Anonymization v. pseudonymization
Note that for the purposes of data privacy, there's a difference between anonymization and pseudonymization. Recital 26 of the General Data Protection Regulation states that data has been anonymized when it is "rendered anonymous in such a manner that the data subject is not or no longer identifiable."
Article 4(5) of the defines pseudonymization as "the processing of personal data in such a manner that the personal data can no longer be attributed to a specific data subject without the use of additional information"