A Persistent Identifier (PID) is a permanent digital code directly associated with a digital resource, such as a dataset, scholarly article, or other publication, making it permanently identifiable and findable. Unlike other serial identifiers (e.g., URLs), a Persistent Identifier refers to the object itself rather than its location on the internet. If the location of a digital object associated with a Persistent Identifier changes, the identifier remains the same; only the URL location in the identifier database needs to be updated or supplemented. This ensures that a dataset remains permanently findable, accessible, and citable (Forschungsdaten.info, 2023).

PIDs play a central role in the FAIR (Findable, Accessible, Interoperable, Reusable) use of research data'Data that are a) created through scientific processes/research (e.g. through measurements, surveys, source work),  b) the basis for scientific research  (e.g. digital artefacts), or c) documenting the results of research, can be called research data.This means that research data vary according to projects and academic disciplines and therefore, require different methods of processing and management, subsumed under the term research data management” (Forschungsdaten.info, 2023). Read More and are explicitly mentioned in the FAIR PrinciplesThe FAIR Principles were first developed in 2016 by the FORCE11 community (The Future of Research Communication and e-Scholarship). FORCE11 is a community of researchers, librarians, archivists, publishers, and research funders aiming to bring about change in modern scientific communication through the effective use of information technology, thereby supporting enhanced knowledge creation and dissemination. The primary goal is the transparent and open presentation of scientific processes. Accordingly, data should be made findable, accessible, interoperable, and reusable (FAIR) online. The objective is to preserve data long-term and make it available for reuse by third parties in line with Open Science and Data Sharing principles. Precise definitions by FORCE11 can be found on their website see: https://force11.org/info/the-fair-data-principles/. Read More. Research data should be accessible, interoperable, and reusable, but they must first be discoverable. Globally unique and persistent identifiers are essential for identifying published resources and providing machine-readable metadataMetadata are descriptions of research data (data about data) and provide content-related and structured information about the research context, methodological and analytical procedures, as well as the research team that generated the data. They can be categorized into bibliographic, administrative, procedural, and descriptive metadata and are typically created using templates, ReadMe files, or data curation profiles. Metadata are published alongside the research data themselves and are essential in online repositories and research data centers, where they enable third parties to understand and contextualize datasets. Metadata also enhances the findability and machine-readability of data, making them a key component of the FAIR Principles and good scientific practice. Read More. PIDs are not only assigned to datasets and publications but are relevant for all aspects of the research data lifecycleThe research data lifecycle model represents all the phases that research data can go through, from the point of collection to their reuse. These phases are linked to specific tasks and may vary (Forschungsdaten.info, 2023). Generally, the research data lifecycle includes the following stages: Read More, including the researchers themselves, as well as organizations and funding institutions.

Examples of persistent identifiers are DOIDOI stands for Digital Object Identifier, a unique and permanent (persistent) identifier for digital objects, such as articles and contributions in scientific publications, as well as lecture publications and educational materials. A DOI must first be registered in the central database of the International DOI Foundation see: https://www.doi.org/. Read More and ORCIDAn example of a standardized identifier for uniquely identifying individuals is the ORCID (Open Researcher and Contributor ID). ORCID is an internationally recognized persistent identifier that allows researchers to be uniquely identified. The ID can be used by researchers for their scientific publications permanently and independently of any institution. It consists of 16 digits, grouped in four sets of four (e.g., 0000-0002-2792-2625). ORCID IDs are widely established in workflows at numerous publishers, universities, and research-related institutions and are often integrated into the peer-review process for journal articles An ORCID can be created free of charge at https://orcid.org/.. Read More.