Pseudonymized data is defined in the fifth definition of art. 4 of the GDPR. Unlike anonymising, pseudonymising is not a method to make data unidentifiable. It actually is a way of protecting personal data in a safer manner. It is a legal term that means that personal data can no longer be linked to an individual unless additional data is used. This additional data has to be saved separately, and in a secure way, with sufficient technological and organisational safeguards. An often-used way to pseudonymise is by replacing the data with a series of characters. In that case, the original data can only be retrieved with the right key.