A DOI, or a Digital Object Identifier, is what is being called a persistent identifier. It offers a reference to an object somewhere available on the internet. A DOI is a code which, when prefixed with ‘https://doi.org/’ leads you to a webpage, also landing page, describing the object. DOI’s in the Netherlands are being distributed by DataCite. Before DataCite hands out a DOI, it demands a minimal set of metadata, which is used to fill the landing page. All objects with a DOI are at least findable in the data catalogue of DataCite. Some DOI’s, e.g. those of the 4TU repository, Yoda and the Dutch DataVerses, are ‘harvested’ by the Data Archiving Network Service (DANS) and also findable in the data catalogue of DANS Narcis.