Uniform Resource Identifier (URI)

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A Uniform Resource Identifier (URI) provides a uniform mechanism for identifying a resource.

A resource identified by a URI may be physical, digital, conceptual, or abstract. The identified resource does not need to be accessible through a network.

Examples of things that may be identified by a URI include:

• documents
• images
• services
• namespaces
• schemas
• concepts
• vocabulary terms
• organizations
• people
• other identifiable resources

A URI uses a URI scheme to establish the rules governing its syntax and interpretation.

Examples of URI schemes include:

• http
• https
• mailto
• urn
• tel
• ftp

A URI may function as a name, a locator, or both.

A URI does not imply that the identified resource can be retrieved or accessed over a network.

an identifier consisting of a sequence of characters used to identify a physical, digital, conceptual, or abstract resource

• RFC 3986, Uniform Resource Identifier (URI): Generic Syntax

A Uniform Resource Locator (URL) is a subset of URI that identifies a resource and also provides a means for locating or accessing that resource.

The general term URI should be used when the distinction between identification and location is not significant.

The following are examples of URIs:

https://example.org/resource/123
urn:example:object:123
mailto:user@example.org
tel:+1-555-555-1212

The first example may function as both an identifier and locator, while the urn, mailto, and tel examples illustrate other URI schemes.