Persistent identifiers (PID) are used to uniquely identify a specific entity in an online environment, such as a publication, research data, or a person. A persistent identifier ensures that a link remains functional even if the physical location of the resource on the web changes. Persistent identifiers also enhance the reliability, reproducibility, and citability of information, and support the implementation of FAIR principles.
The most common identifier systems for publications and data-related materials are DOI and URN, while the ORCID iD is used to uniquely identify researchers.
DOI (Digital Object Identifier) is an internationally standardized and managed identifier system. A DOI provides a persistent link through which either the object itself or its metadata can be accessed online. Typically, research outputs (such as scientific articles and research data) receive a DOI directly via the publisher or the data repository. Research organizations themselves may also have a need to assign DOIs, for example to meet long-term preservation requirements for research data. Tampere University has joined the DataCite Finland consortium, coordinated by CSC – IT Center for Science, which enables the university to assign and manage DOIs for research data and metadata.
Similar to DOI, URNs (Uniform Resource Names) are unique and persistent identifiers intended for online publications. However, unlike DOIs, URNs can incorporate other identifiers as part of them, such as ISBN or ISSN numbers. In Finland, the National Library maintains the URN registry for universities and research institutions, and URN identifiers are used in publication repositories maintained by the National Library, such as Trepo and Theseus. When you publish your work (most commonly a thesis, dissertation, or monograph) in Trepo or Theseus, the system automatically assigns a URN link to the publication.
The ORCID iD is an open, public, international, and community-driven identifier system that provides a persistent and unique digital identifier, helping researchers distinguish themselves from others. The Open Science policy of the Tampere higher education community recommends that researchers obtain an ORCID iD and use it in all their scholarly activities. You can read more about ORCID and how to obtain one on the Researcher's guide page Researcher identifiers and profiles.
