This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Here is a reasonable explanation. For the most part, URL and URI are essentially the same thing. But whereas a URL is like an address, a URN is like a name, and you need to use a URN resolution service to look up the address (i.e., the URL/URI) that goes with it. Since such services aren't widely available, URNs aren't much more than a curiosity right now. [ March 26, 2004: Message edited by: Ernest Friedman-Hill ]