Jason in a Nutshell

All about programming and whatever else comes to mind


Posted by Jason Baker on May 14, 2008

Ok, so this is one issue that’s been bugging me about HTTP. I keep hearing the acronyms URI and URL mentioned. I knew that URL wasn’t technically accurate, but I couldn’t ever find a good explanation of what the difference between the two are or why URI is more technically accurate. This is even after reading various explanations about the subject. Here’s what I’ve come up with:


A URI is a name that identifies something globally. Admittedly, this explanation is a little bit vague, but then again the idea of a URI is kind of a vague concept. We’ll come back to this later, but I’ll give you a few examples of URIs:

  • http://www.coderspalace.com
  • http://www.coderspalace.com/index.php
  • file://usr/lib/python


A URL is a special kind of URI. It gives you more precise instructions on where something is located. Thus, something like http://www.coderspalace.com/j_baker/ will tell you what computer a webpage is and will even narrow down where the webpage is located, but it won’t give you an exact location of the file like http://www.coderspalace.com/j_baker/index.php will.

So I suppose the next question is: who cares? The point is that nowadays you don’t really need the level of precision that a URL requires and haven’t for a long time. Try going to http://www.coderspalace.com/j_baker/ and http://www.coderspalace.com/j_baker/index.php and see if you get any difference between the two links. You won’t. This is because my webserver is smart enough to know that when you go to http://www.coderspalace.com/j_baker/ you really mean http://www.coderspalace.com/j_baker/index.php. Pretty cool, huh?


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