Should I use a relative or absolute url?
There is nothing more annoying then moving a website to a new domain name, and finding you, or somebody else, used a ton of absolute links.
Now you have to scour code and articles to fix them, since they are pointing to the old domain. Is there a better solution? Enter, relative links.
oookay, first things first. What’s the difference?

An absolute link uses the entire domain name to point to your resource. so if you want to include a url in your website, if you used a absolute link it would look like this.

You can see there is a full url path included. (ht tp: // www.fancywebsite.com)
Now, a relative link is when the server already knows where the file or resource is. A relative link looks like this.

In this example you can see there is no full url such as a .com

Relative URLs are great if you move your site. With Joomla 1.5 you have very little changing to do in your configuration.php. You only have to change 2 values in that file and your site is moved. If you are in the habit of using absolute urls in your content, your website designs, or your images, now is the time to fully understand how cool relative links are, and how they will save you considerable amounts of time over the long haul.
Tags: development, Joomla, useful tips
Your statement: Relative URLs are great if you move your site. With Joomla 1.5 you have very little changing to do in your configuration.php. You only have to change 2 values in that file and your site is moved.
Question: what are the 2 values to change in the config.php file? I have massive sites and need to change everything to relative links.
My 2 cents : As a SEO guy, relatives URLs are really a nightmare because of duplicate issues.
Today I audited a Joomla website with 150 real urls and more than 8000 urls known by search engines because of bad use of relative urls.