The World Data System (WDS) was created in October 2008 as an Interdisciplinary Body of the International Council for Science (ICSU), building on the 50+ year legacy of the World Data Centres and Federation of Astronomical and Geophysical data analysis Services established by ICSU to manage data generated from the International Geophysical Year (1957–1958). ICSU-WDS is striving to build worldwide ‘communities of excellence’ for scientific data services by certifying holders and providers of data or data products—and networks of these—from wide-ranging scientific domains using internationally recognized standards. Certification criteria and a procedure for evaluating candidates for membership were developed by the WDS Scientific Committee (WDS-SC) to ensure the trustworthiness of WDS Members in terms of authenticity, integrity, confidentiality, and availability of data and services. Certification is important because it promotes confidence in the usability and persistence of shared data resources. It also helps data services improve their practices and procedures.