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

See this document. Specifically,

a URL is a type of URI that identifies a resource via a representation of its primary access mechanism (e.g., its network "location"), rather than by some other attributes it may have.

It's not an extremely clear term, really.