Glossary · Semantic web foundations

IRI (Internationalized Resource Identifier)

Also known as: Internationalized Resource Identifier, URI, resource identifier

An IRI (Internationalized Resource Identifier) is a globally unique identifier for a resource, defined in RFC 3987. It generalizes the URI by allowing Unicode characters, and it is how RDF and iiRDS name every class, property and resource.

Semantic web
Ontology
Information architecture

In one sentence

An IRI is a Unicode-capable, globally unique identifier — the name of every class, property and resource in RDF and iiRDS.

Example

http://iirds.tekom.de/iirds#Topic is the IRI of the iiRDS Topic class; https://example.com/iirds/io/1312 is the IRI of one topic.

How it applies

iiRDS: The iiRDS core vocabulary uses the namespace http://iirds.tekom.de/iirds#; domain extensions use sub-namespaces below http://iirds.tekom.de/iirds/domain. Proprietary extensions are registered in the defining company's own namespace, and identity and classification domains must have absolute IRIs.
Technical documentation: An IRI identifies a resource, it does not have to be a web address that resolves. Stable IRIs for topics, components and products are what make content reusable across systems and releases.
Governance: Choose IRIs that do not change when content moves — avoid file paths, system names or version numbers in the IRI of a stable resource.
AI and linked data: IRIs are how a knowledge graph knows two statements are about the same thing. Every term in this glossary has one, so AI systems can cite it unambiguously.

IRI vs. URI vs. URL

A URI is limited to ASCII characters; an IRI may contain Unicode, such as https://example.com/produkte/lüfter. A URL is a URI that also tells you where to retrieve the resource. Every URL is a URI, and every URI is an IRI.