Special thanks to Jesse Long for permission to use text from the National Transportation Library's guide on persistent identifiers.
In this guide we cover two types of Persistent Identifiers (PIDs):
DOIs are the most common type of identifier for digital objects, particularly for scholarly, research, and technical publications. "Digital Object Identifiers (DOIs) are globally unique character strings that reference physical, digital, or abstract objects. They provide actionable, interoperable, persistent links to information about the objects they reference" (USGS) The DOI has become an important piece of publication metadata that guarantees continued access to, at minimum, the metadata for an object. See the DOI section of this LibGuide for more information on how to request one for your works.
An ORCID iD is a digital identifier for researchers that records professional activities and disambiguates one researcher from another. An ORCID profile connects researchers with their contributions and affiliations over time, despite name changes or different name formats (e.g. John Q. Smith, J. Smith, John Smith, JQ Smith, etc.). It can be connected in some way to most other creator profiles, and is the most interoperable creator PID. ORCIDs can be created and edited by researchers, whereas the other identifiers listed here are created automatically or by a governing body. See the ORCID section of this LibGuide for more information about their value to you and how to register for one.
A PID is a long-lasting digital reference to an object, contributor, or organization. Web URLs are an example of a common identifier - Web URLs can break. The term "persistent" refers to the need for an identifier to provide continued access to and provenance for the object it refers to for years to come.
The long-term persistence of identifiers for objects, contributors, and organizations is vital to robust data management strategies. Publishers, funders, and other organizations have implemented PIDs in their established research workflows to enable the creation of trusted digital connections between objects, contributors, and organizations.
PID is a new name for a concept that has been a part of publishing for decades (e.g. ISBNs and ISSNs to distinguish textual objects). The proliferation of digitally available research and technical publications has created a need for machine-readable, interoperable PIDs. Machine-readable PIDs such as DOIs and ORCID iDs are valuable assets in enabling information sharing across systems.