What is an Add-on Domain?
An Add-on Domain is a domain name that that points to a subdirectory within your main cPanel account. For example, if your main domain on your account is mywebsite.com and you would like to have a separate website for another domain name called yourwebsite.com, this feature would allow you to create yourwebsite.com in it's own directory.

Your add-on domain would use the same name servers as your main domain for your hosting account.

How do I add an Add-on Domain?

To add a domain to your main account, follow the steps outlined below:

Preliminary step: Update your domain's Name Servers with your domain name registrar

The initial step in getting your add-on domain to work is configuring the domain with the domain name registrar (like GoDaddy.com or Register.com) that you purchased the domain from. The name servers for your add-on domain will be the name servers that your main domain on your account are using.

Step 1: Log into cPanel.

To log into cPanel, you should go to http://www.yourdomain.com/cpanel/ (where www.yourdomain.com is replaced by your account domain name).

Step 2: Locate the Addon Domains link on the main screen upon login.

You will see this link after logging in (usually on the top row, on the right side).

Step 3: Complete the Addon Domains procedure.

Under Current Addon Domains, complete the form according to the fields as described below:

New Domain Name: In this field, you should enter the domain name that will be your add-on domain. (According to the example given at the beginning of this tutorial, yourwebsite.com would be entered here.)

Username/directory/subdomain Name: In this field, you should enter the name of the sub-directory that will represent the physical location of your add-on domain on the server. This name can be anything you want, except it can't be a directory that already exists. (In the example, the value yourwebsite could be entered here.)

Some tips:

Do not use any back-slashes, forward-slashes, or special-characters for this field.
Keep the entire value in lowercase letters.
Do not use any spaces in the value either.
The value you enter here will represent the directory created under your public_html directory on the server. (In the example that we've been following, it woud be /public_html/yourwebsite/). All the files you want to appear when somebody goes to this domain in their web browser would be put in this directory.

Password: In this field, enter a password that will be used by the Username (the value you put in the field above) to access this directory by FTP. Please only use letters and numbers. Also, remember that your password is case-sensitive so it is important that you remember your uppercase and lowercase characters when you type this password.

Step 4: Click Add Domain! to complete the procedure!

Now that you've finished the Add-on Domain procedure, you need to add your files to the directory you just created so that your visitors see something when they go to this website!

Some important notes:

Your add-on domain may not start "working" until your name server changes (that you performed in the Preliminary Step) take effect. This can take anywhere from 24 to 72 hours and usually cannot be prevented.