What is the difference between a URI, a URL and a URN?

Question

People talk about URLs, URIs, and URNs as if they\'re different things, but they look the same to the naked eye.

W

Answer 1

Here is my simplification:

URN: unique resource name, i.e. "what" (eg urn:issn:1234-5678 ). This is meant to be unique .. as in no two different docs can have the same urn. A bit like "uuid"

URL: "where" to find it ( eg https://google.com/pub?issnid=1234-5678 .. or ftp://somesite.com/doc8.pdf )

URI: can be either a URN or a URL. This fuzzy definition is thanks to RFC 3986 produced by W3C and IETF.

The definition of URI has changed over the years, so it makes sense for most people to be confused. However, you can now take solace in the fact that you can refer to http://somesite.com/something as either a URL or URI ... an you will be right either way (at least fot the time being anyway...)