According to Article 42 of the GDPR, the Commission may approve certification mechanisms, seals and marks for the purpose of demonstrating the existence of appropriate safeguards for personal data transfers to third countries or international organisations. These certification mechanisms, seals and marks are voluntary and transparent, and are issued by accredited certification bodies or by the competent supervisory authorities. They are subject to the general provisions on certification in Articles 42 and 43 of the GDPR. They are intended to enhance the trust of data subjects and facilitate the free flow of personal data within the Union and beyond. They are also subject to periodic review and withdrawal or suspension if the conditions for certification are not or are no longer met. Reference:
Article 42 of the GDPR
European Data Protection Law & Practice textbook, Chapter 8: Transfers of Personal Data to Third Countries, Section 8.3: Appropriate Safeguards, Subsection 8.3.4: Certification Mechanisms, Seals and Marks Guidelines 1/2018 on certification and identifying certification criteria in accordance with Articles 42 and 43 of the Regulation