What is the difference between URI's and URL's?

Davanum Srinivas

Here is a snippet from the XML Bible written by Elliotte Rusty Harold.

"URI stands for Uniform Resource Identifier. URIs are similar to URLs but allow for more precise specification of a linked resource. In theory, URIs separate the resource from the location so a web browser can select the nearest or least congested of several mirrors without requiring an explicit link to that mirror.