People talk about URLs, URIs, and URNs as if they\'re different things, but they look the same to the naked eye.
W
Another example I like to use when thinking about URIs is the xmlns attribute of an XML document:
some text
In this case com.mycompany.mynode would be a URI that uniquely identifies the "myPrefix" namespace for all of the elements that use it within my XML document. This is NOT a URL because it is only used to identify, not to locate something per se.