URL stands for Uniform Resource Locator, which is also a fancy technical term for "website address."

Lets disect the following URL:

http://www.widgets-r-u.com/support/contact.html

http:// is the protocol. The protocol has to do with how the data is transferred between the server and client. It's the protocol you will probably see 99% of the time. Another one you might see occasionally is https:// which is a "secured" or "encrypted" connection often used for forms where sensitive data is being entered (i.e. credit card numbers). Virtually all web browsers assume the http:// protocol if it is not included when entering a URL in the browser address bar.

www.widgets-r-us.com is the domain name. The domain points to the web-server which the website resides.

/support is the directory path. In other words, it determines which folder or sub-folder on the webserver's file-system in being viewed. If a directory is not included in a URL, the "root" directory is assumed.

/contact.html is the filename. It determines which file on the webserver's file-system is being viewed. If a filename is not included in the URL, a file called "index" is usually assumed for most webservers.

Therefore, it is wise to name your homepage file "index" (i.e. index.html) and store it on the webserver's root directory.

By naming the homepage file "index", you do not have to include the filename in your homepage's URL, shortening your website address.

By storing your homepage file in the root directory of your webserver, you do not have to include a directory path in your homepage's URL either, further shortening your website address.

Therefore after the web browser assumes the http:// protocol, your homepage's URL can be shortened just the domain name, which makes it much easier to remember.

Related Articles:

The Anatomy of an E-mail Address
userID@domain

URL Forwarding
Masked and Unmasked