URL, URI and URN

[Sandeep Jindal]

Hello,
I am new to XML. I know that URL and URN are part of URI. But i m confused for the difference between URL and URN.
Please explain with apropiate example

[Lasse Koskela]

A URL (Uniform Resource Locator) is a kind of address while a URN (Uniform Resource Name) is just a name without any hint about the actual location of the particular resource.
For example, "http://www.google.com" is a URL while "urn:google" is a URN.

[Sandeep Jindal]

Thanks Lasse,
So you mean to say that any valid string "google1", "google.com", "1google", "1-google", "1.google" is a URN
or in better words a namespace. Or there is some restriction on the URN?

[Lasse Koskela]

There are some rules, which are listed in RFC 2141. For example, a valid URN must begin with the "urn:" prefix.