Anonymisation means the transformation of personal data into a form that irreversibly prevents the identification of an individual person. This may mean, for example, removing direct identifiers and simplifying the data to a general level so that personal data cannot be reconstituted in any way.

Pseudonymisation refers to the transformation of personal data, for example into a coded form. In this case, names and personal identifiers can be removed and replaced by another unique identifier, i.e. a code. Often a code key is kept to restore direct personal data to the data. Pseudonymised data are still personal data.