URI versus URN versus URL

This post is mostly a bookmark so that I can easily find this reference to a discussion of using URI's versus URN's. See Sean McGrath's post entitled "HTTP URIs rather than URNs for identifiers." A URI (Uniform Resource Identifier) is essentially a URL used for the purpose of permanently detailing the specific identity for a resource. A URL (Uniform Resource Locator) specifies the location of a resource. A URN (Uniform Resource Name) specifies a resource as a name in a name space.

Here are some web resources:

• Uniform Resource Names (urn)
• Naming and Addressing: URIs, URLs, ...
• URIs, URLs, and URNs: Clarifications and Recommendations 1.0

Technorati: URI, URN, URL.

-- Jack Krupansky