A.P. Lawrence

2005/04/29 URL,URI,URN and URC

"What's a URI?"

I was momentarily confused. Why was this young woman asking me this question? I was at LinuxWorld, had just stopped at a booth to sign up for a magazine subscription. Why was she asking me about URI's? Was this some sort of test?

"It means Uniform Resource Identifier. Like a web page; http://whatever.com" I answered, probably with a quizzical look on my face.

"Then what's a URL?"

I paused from filling out the subscription information. "That's a Uniform Resource Locator". Now I hesitated. This whole area is muddled enough, but why was she asking? Well, one way to find out: I added "Why?"

"Because I've been asking people all day and nobody knows. Everybody knows what a URL is, but this form asks for a URI, so there must be a difference."

"Umm, not really", I said. "I think at one time some people wanted there to be a difference, but nowadays it usually means the same thing." I finished filling out the subscription form and got away from there as quickly as I could, because I certainly wasn't going to try to explain what that difference might be. And I sure as heck didn't want to get into URN's and URC's either. This stuff gets really geeky for no reason that most of us can fathom.

RFC 1630 defines URI's and RFC 1738 defines URL's. According to RFC 1630, a URL is a type of URI, so 1738 is just further explanation. The other type is a URN, which is supposed to be more consistent, and is actually just more confusing (in my opinion, of course). Don't even get me started about URC's: what the heck is "URC's are thought of as collections of metadata about some data" supposed to mean? The more people try to explain this the more confusing it gets.

Does it matter? For most of us, no. Technical distinctions like this are far too esoteric even for the ordinary geek, never mind the ordinary human. If somebody wants to argue because a form asks for the URI of your web page when it should have said URL, well, happy trails to them, and they are welcome to play that particular game with someone else, but not with me. Life is too short for that nonsense.

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