There are over 1000 data resources in Europe. Only a small fraction of these have institutional support and long-term funding commitments. The fact that the survival of many crucial bioinformatics resources in the mid- and long-term is not guaranteed is threatening the foundations of academic and industrial life science activities, and risks the loss of an immense wealth of biological and medical information as well as the associated investments. Identifying ways to assess the quality and impact of these crucial data resources will (a) promote excellence in resource development and operation to support capacity building through spreading best practice, and (b) provide a basis for technical and science policy actions required to support the long-term sustainability of the data resources that are the backbone of bioinformatics infrastructure. The ELIXIR Core Data Resources are defined as a set of European data resources that are of fundamental importance to the broad life science community and the long-term preservation of biological data. They provide complete collections of generic value to life science, are considered an authority in their field with respect to one or more characteristics, and show high levels of scientific quality and service. Thus, ELIXIR Core Data Resources are of wide applicability and usage.