A PID (persistent identifier) is a unique digital ID number or a unique code string that permanently identifies an object, a person, or an organisation. In a digital context, a PID is used as a link between an object and websites, files, documents, and other objects.

There are different types of PID depending on what needs to be identified and which organisation is behind the PID. Common PIDs are, for example, ISBN (International Standard Book Number) for books and ISSN (International Standard Serial Number) for magazines. Researchers and other academics use ORCID (Open Researcher and Contributor ID), and the ROR (Research Organization Registry) identifier is becoming established among research organisations. The research data that are made visible in the SND research data catalogue receive a DOI (Digital Object Identifier). The DOI is a link to a complete data description that remains the same, regardless of where the data files are located or if they are moved. (If the data are deleted, this will be entered on the study information page.) One purpose of appending a DOI to data is to make it possible to make unique citations of a certain version of a data material. Such citations guarantee that you as a researcher are acknowledged if the data from your project are reused. It is often a requirement from journals that in order to publish articles or studies based on research data, the data need to be accessible and referenced by a PID.

Example of a DOI:

This DOI points to Swedish version of The National SOM Survey 1995, version 1.0. If the SOM Institute decides to create a new version of this same dataset and make it accessible, the new version would receive a new DOI. That way, there is no doubt about which version a particular published analysis of the data is based on.


As a researcher you have every reason to want to create, maintain, and use an ORCID. By doing so, the data, publications, and other scientific creations you have contributed to can be uniquely identified, even if you have the same name as another researcher, or if you change your name. It also makes it easy to link to a list of publications or a CV. Many research funding bodies and journals require that you have an ORCID if you apply for a grant or submit an article.