What is an URL?
An URL (Universal Resource Locator ) or URI (Uniform Resource Identifier) is used to address a document (or other data) on the World Wide Web. If you look at the top of your browser in the address field you will see a location box with:
http://www.kdwebpagedesign.com/tutorials_02.asp
This is the full Web address or URL of the first page of our Tutorial section. To be viewed on the Web, your images and HTML documents MUST be uploaded to a computer (server/host) that is configured to be used on the Internet.
Absolute and Relative URLs
There are two basic types of URLs: absolute and relative. They each have their place for use in links on your Web page. Absolute URLs specify the location of a file using a full address, and work identically no matter where in the world you are. Relative URLs specify the location of a file using a partial address relative to your site.
TIP: Use absolute URLs when linking to a different site, and relative URLs when linking within your site.
The absolute URL of the image below looks like this:

The relative URL of the image above looks like this:

Besides using HTTP, the other schemes you may run across are: file (a file on your local PC); ftp (a file on an FTP server); gopher (a file on a Gopher server); news (a Usenet newsgroup); telnet (a Telnet connection) and WAIS (a file on a WAIS server).
If you use the incorrect URL with your HTML tags the dreaded
will appear instead of images, or if you are trying to link to another document, ACTION CANCELED or PAGE NOT FOUND is all that you get.
When using your own HTML on eBay, you will need to always use absolute URLs since your HTML is on eBay's server, while your images will be on your own server.
IMPORTANT: Do not EVER EVER EVER direct link an image from someone else's server unless you have that persons permission. This is considered image and bandwidth theft. And always remember to get permission to use the image. Just because an image is on the Internet does not mean it is public domain.