What exactly are these “persistent identifiers,” though? A persistent identifier, often known as a persistent identifier or PID, is a reference to a document, file, web page, or other digital entity that remains valid over time. The vast majority of PIDs are equipped with a one-of-a-kind identifier that is connected to the most recent address of the metadata or content.
Long-term persistence of IDs for objects, contributors, and organizations is essential for effective data management techniques. PIDs have been incorporated in established research workflows by publishers, funders, and other organizations to enable the construction of trusted digital linkages between objects, contributors, and organizations.
PID is a new moniker for a notion that has been around for decades in publishing. Previously, ISBNs and ISSNs were employed by publishers to differentiate unique textual objects . The rise of digitally available research and technical publications, on the other hand, has created a demand for machine-readable, interoperable PIDs. DOIs and ORCID iDs, for example, are machine-readable PIDs that can be used to share information between systems.

Common PIDs

Contributor Identifiers

International Standard Name Identifier (ISNI)
ISNI (ISO 27729) “is the ISO certified global standard number for identifying the millions of contributors to creative works and those active in their distribution, including researchers, inventors, writers, artists, visual creators, performers, producers, publishers, aggregators, and more” (ISNI-IA, 2023) and serves to decipher contributor names to improve search and discovery. ISNI’s objective is “to resolve the problem of name ambiguity in search and discovery.” ISNI identities and ORCID identifiers are interchangeable. ISNI is a global standard regulated by the International Organization for Standardization (ISO), whereas ORCID iDs is an open registry where researchers can create and maintain their own identification page.
Contributor identifiers include researchers, authors, scientists, and so forth. Contributor IDs create a profile for a work’s contributors that distinguishes them from others. Contributors with the same or similar names can use unique identifiers to track citations to their study.

Open Researcher and Contributor Identifier (ORCID iD)

An ORCID iD is a unique identifier for academics that tracks professional activities and distinguishes one researcher from another. An ORCID profile links researchers to their contributions and affiliations over time, regardless of name changes or alternative name forms (e.g., John K. Kamau, J.Kamau, John Kamau, JK Kamau, and so on). It is the most interoperable creator PID and can be linked to most other creator profiles in some fashion. ORCID identifiers can be produced and changed by researchers, whereas the others listed above are either automatically or by a governing body.


In the Web of Science publishing ecosystem, ResearcherID is a unique identifier that connects researchers with their papers. ORCID iD profiles can be linked to ResearcherID profiles.

Scopus Author ID

Scopus Author IDs are assigned automatically to writers whose works have been indexed in Elsevier’s Scopus abstract and citation database. ORCID iDs can be connected to Scopus Author IDs.

Object Identifiers
The term object is purposefully wide, referring to “a meaningful piece of data”. Books, articles, white papers, chapters, databases, tables, figures, films, and so on are examples of objects. A single resource, such as a book, may be associated with numerous object identifiers, such as one for the entire book, one for each chapter, and one for individual figures inside chapters. The following are examples of digital object identifier systems.

Archival Resources Key (ARK)

The ARK scheme is supported by three criteria that are built on links: from the object to a promise for stewardship, from the object to metadata that characterizes it, and to the object itself. An ARK identifier is a “specially constructed, globally unique, actionable URL.”

Digital Object Identifier (DOI)

A digital object identifier, or DOI, is not the same thing as an identification of a digital item. Instead, a DOI is a “digital identifier of an object,” which means that it can be allocated to any object, regardless of whether or not it is digital. DOIs are “unique, permanent numbers assigned to specific objects, which remain unchanged” , citing Digital Object Identifiers] [DOIs]. DOIs are the most prevalent kind of identifier for digital things, especially within the realm of scholarly, scientific, and technical publications. For further details, please refer to the section of this LibGuide titled “DOI.”

Handle (HNDL)

Handle is typically used as an underlying architecture for identifier systems such as the DOI system, but it can also be used as a standalone identifier system.

Persistent Uniform Resource Locator (PURL)

“A naming and resolution service for general Internet resources” is what the PURL system delivers to its users. A PURL is a URL that “points to a resolution service instead of the actual location of a digital resource,” and the resolution service then redirects to the current URL of the resource [6]. PURLs are becoming increasingly popular as an alternative to traditional URLs. PURLs are a type of long-lasting URL that can be used repeatedly and point to resolution services that keep information on the present location of a resource. ARKs, DOIs, and HNDLs are all examples of PURLs

Organization Identifiers

Research institutions, corporate funders, government agencies, and other types of organizations are all included in the scope of organization IDs. In contrast to object and creator IDs, which are more firmly established and widely used, organizational identifiers are still in the process of being developed. The purpose of organization IDs is to facilitate the establishment of unambiguous and permanent links between the organizations that provide assistance to artists and the production of items.

Funder ID

Funder IDs can be found in the Crossref Funder record, which describes itself as “an open and unique registry of persistent identifiers for grant-giving organizations around the world” . Funder IDs increase research funding transparency by connecting research to grant and funder information.

Research Organization Registry (ROR) ID

ROR IDs are identifiers for research organizations that are “globally unique, stable, discoverable, and resolvable” . To enable interoperability, ROR IDs store metadata about organizations “such as alternate names/abbreviations, external URLs, and other identifiers, such as Wikidata, ISNI, and the Open Funder Registry” . The ROR ID database is built on GRID seed data.

 Project Identifiers

The Research Activity Identifier (RAiD)

The Research Activity identification (RAiD) is an example of a compound object identification. RAiD was created in 2017 to serve as an actionable research activity tracking record. It was envisioned as an identifier (a Handle) with associated metadata that would capture the individuals, organizations, financial sources, equipment, and other research entities associated with the development, curation, and preservation of a dataset.

It rapidly became evident that RAiDs might be highly useful as a project identifier, because capturing the entities, responsibilities, and interactions around a uniquely defined activity profile may both reflect and supplement existing project management tools. In the context of open research, it also gives a record of the background for and contributions to each output, which is critical for research integrity and reproducibility.