An addon domain is a fully functional domain name attached to an already existing web hosting account via a control panel, such as cPanel. This will allow you to create additional services, websites, email addresses and fowarders, all within the same control panel as your primary domain.
The most common reason to use addon domains is simply to allow for the creation of multiple websites, under multiple domain names, without having to sign up for separate hosting accounts. This will prove useful if you plan on creating multiple websites that may not require an entire web hosting service to itself.
How do they work?
Addon domains are easy to set up. They work by creating a subdirectory within your existing directory, dedicated to the new addon domain. Once created, it will set up 3 URL access paths:
The new directory can then be used to house an entirely new set of files and applications for a website unique to the addon domain and has no impact on the primary domain name, as it functions as an independent domain name and website.