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Records Authority
Category: Metadata Standards

Persistent Identifier

Also known as: PID, Persistent Unique Identifier
Simply put

A persistent identifier is a long-lasting label, typically made up of letters and numbers, that gives a unique name to a digital resource, person, place, or other entity and helps locate it over time. Unlike an ordinary web address that may change or break, a persistent identifier is intended to remain a reliable reference even as the location of the resource changes. Familiar examples include identifiers assigned to research outputs and to individual researchers.

Formal definition

A persistent identifier (PID) is a long-lasting, unique reference to a digital resource or other entity such as a document, file, web page, person, or concept. It typically comprises two components: a unique identifier string that names the entity, and a resolution or location service that maps that identifier to the current location of the resource, allowing the reference to remain stable even when the underlying location changes. PIDs are widely used in digital preservation and scholarly contexts; examples referenced in the evidence include DOI, ORCID (which uniquely identifies an author across a career), and ROR. A persistent identifier is a mechanism for stable identification and location rather than a guarantee of the persistence, integrity, or authenticity of the identified resource itself, which depend on separate management and preservation practices.

Why it matters

Persistent identifiers address a recurring problem in digital environments: the references used to locate a resource often break as systems, domains, and file structures change over time. An ordinary web address may cease to resolve when content is moved or reorganized, undermining the ability to reliably cite, retrieve, or verify a resource. A persistent identifier is intended to remain a stable reference even when the underlying location shifts, which supports continuity of access across the extended timeframes that digital preservation and scholarly recordkeeping typically require.

For records management and digital preservation, this stability matters because references embedded in citations, metadata, and links between resources need to remain usable well beyond the lifespan of any single storage location or system. Persistent identifiers help maintain the connective tissue between resources and between resources and the people, organizations, or concepts associated with them, reducing the risk that references degrade into broken links over time.

It is important to note the limits of what a persistent identifier provides. A PID is a mechanism for stable identification and location; it is not, on its own, a guarantee of the persistence, integrity, or authenticity of the identified resource. Those properties depend on separate management and preservation practices. Treating a PID as evidence that a resource remains unchanged or authentic would overstate its function, and professionals should keep the distinction clear when relying on PIDs within a broader preservation or recordkeeping framework.

Who it's relevant to

Digital preservation practitioners
Those responsible for long-term preservation rely on persistent identifiers to maintain stable references to resources across changes in systems and storage locations. Practitioners should understand that a PID supports stable identification and location but does not by itself ensure the integrity or authenticity of the identified resource, which remain the responsibility of separate preservation controls.
Records managers and archivists
Persistent identifiers can help keep references within metadata, citations, and links between resources usable over time, reducing reliance on location-based addresses that may break. Records managers should treat PIDs as one element of stable referencing rather than a substitute for the practices that establish and preserve a record's authenticity, reliability, integrity, and usability.
Researchers and scholarly communication staff
In scholarly contexts, PIDs such as DOIs for research outputs, ORCID for individual researchers, and ROR for organizations provide unique, long-lasting references that support consistent citation and attribution. This is relevant to those managing research outputs, author identity, and organizational affiliation across the course of a career or a body of work.
Information governance and metadata professionals
Those designing metadata schemes and governance policies may incorporate persistent identifiers to strengthen the durability of references across information systems. They should be aware that the persistence of a PID depends on the continued operation of its resolution service and associated management practices, and should account for that dependency in governance planning.

Inside PID

Identifier string
The stable character sequence assigned to a resource, intended to remain constant even if the resource's location, custodian, or storage system changes over time.
Resolution mechanism
The service or infrastructure that maps the persistent identifier to the current location or metadata of the resource, allowing users to reliably retrieve or reference the resource despite underlying changes.
Associated metadata
Descriptive and administrative information bound to the identifier that supports identification, context, and management of the resource, and that can contribute to establishing authenticity and provenance.
Governance and maintenance commitment
The organizational or institutional undertaking to sustain the identifier and its resolution over the long term, since persistence typically depends on ongoing management rather than the identifier syntax alone.
Namespace or scheme
The framework under which identifiers are issued and kept unique, often administered by a registration authority or community, depending on the identifier system in use.

Common questions

Answers to the questions practitioners most commonly ask about PID.

Is a persistent identifier the same as a URL or web address?
No. A persistent identifier is not equivalent to an ordinary URL. A URL typically points to a location where a resource currently sits, and it may break if the resource is moved, renamed, or reorganized. A persistent identifier is intended to remain stable over time as a durable reference to an entity, often by resolving through an intermediary service that can be updated to point to the resource's current location. The two concepts can overlap when a persistent identifier is expressed in a resolvable, web-friendly form, but the persistence derives from the managed resolution and governance behind it, not from the address string itself.
Does assigning a persistent identifier guarantee that a record will be preserved?
No. A persistent identifier supports stable reference and retrieval, but it does not by itself preserve the underlying record or its content. Persistence of the identifier depends on ongoing governance, maintenance of resolution infrastructure, and organizational commitment. If the referenced object is destroyed, corrupted, or allowed to lapse, the identifier may resolve to nothing or to an error. Persistent identifiers are best understood as one component within broader preservation and recordkeeping arrangements rather than a substitute for them.
How should responsibility for maintaining persistent identifiers be assigned within an organization?
Responsibility is typically allocated through governance arrangements that name who assigns identifiers, who maintains the resolution service, and who updates references when resources move. Depending on organizational policy, this may sit with a records or information management function, an IT or repository team, or a combination working under defined roles. Clear ownership helps ensure that identifiers remain resolvable over time, since persistence depends on sustained maintenance rather than the initial act of assignment.
At what point in the record lifecycle should a persistent identifier be assigned?
This depends on organizational policy and the purpose the identifier is intended to serve. In many cases identifiers are assigned at or near the point of capture, so that a record can be reliably referenced throughout its lifecycle, including during classification, retention, and any subsequent transfer or preservation. Some organizations may defer assignment until a record reaches a more settled or authoritative state. The timing should be documented so that references remain consistent and defensible.
How do persistent identifiers interact with retention and disposition processes?
A persistent identifier can support disposition by providing a stable reference used in audit trails, transfer documentation, and destruction records. When a record undergoes disposition, organizational policy should determine what happens to its identifier: for example, whether the identifier continues to resolve to metadata or a tombstone record after the object is destroyed, or whether it is retired. Because disposition may include transfer or permanent preservation rather than destruction, the handling of identifiers should be defined for each outcome rather than assumed to be uniform.
What governance considerations affect the long-term reliability of a persistent identifier scheme?
Long-term reliability typically depends on sustained funding and maintenance of resolution infrastructure, documented policies for assigning and updating identifiers, and clear accountability for keeping references current. Considerations often include the durability of the chosen scheme, dependence on any external providers or shared services, and continuity arrangements should responsibility change hands. Because persistence is an organizational and operational commitment rather than an inherent property of the identifier string, these governance factors are central to whether identifiers remain usable over time.

Common misconceptions

A persistent identifier guarantees that a resource will remain accessible forever.
The identifier provides a stable reference, but continued accessibility typically depends on sustained governance, resolution infrastructure, and preservation of the resource. Without ongoing maintenance, the identifier may fail to resolve, so persistence is a commitment rather than an automatic property.
A persistent identifier is simply a permanent URL or web address.
A persistent identifier is often expressed in a resolvable form, but its purpose is to remain stable independently of any specific location. A conventional URL points to a location that may change, whereas a persistent identifier is designed to be redirected through a resolution mechanism when the location changes.
Assigning a persistent identifier makes a resource an authoritative record.
A persistent identifier supports referencing and can contribute to integrity and usability, but it does not by itself confer the properties of authenticity, reliability, integrity, and usability that distinguish an authoritative record from a copy, draft, or transitory information. Recordkeeping controls remain necessary.

Best practices

Adopt an established, community-supported identifier scheme rather than devising a bespoke system, so that resolution and governance can be sustained beyond a single project or system.
Assign identifiers as early as practical in the lifecycle and treat them as stable references that should not be reused or reassigned once issued.
Ensure a reliable resolution mechanism is in place and monitored, since persistence depends on maintained infrastructure rather than the identifier string alone.
Bind sufficient descriptive and administrative metadata to each identifier to support identification, provenance, and context over time.
Document organizational responsibility for maintaining identifiers and their resolution, recognizing that long-term persistence is a governance commitment.
Use persistent identifiers alongside, not as a substitute for, recordkeeping controls that establish and preserve authenticity, reliability, integrity, and usability.