If you have a multidomain account (gold or platinum) you may want to manage more than one domain on the same hosting account. You can add an addon domain or a parked domain. Parked domains are useful if you want to have the same website on 2 different addresses (for example you want to show the same website on domain.com and domain.us). It is usually recommended to use a 301 redirect to avoid search engine penalization for duplicated content. Addon domains are domain on their own, as if you had 2 different hosting accounts. When you add an addon domain on your account you're also creating a new folder on your account, that will be used to store your website files.
How to add a parked domain
Once you have logged in into cPanel scroll down to the DOMAINS section, then click on Aliases, insert the name of your domain in the box, then click on "Add Domain". You need to register the domain and point it to your account.
How to add an addon domain
Once logged in the cPanel scroll down to the DOMAINS section, then click on "Addon Domains"
Add the domain name into the field "New Domain Name" then click on save. The other fields will be auto compiled, only edit those if you know what you're doing and need a different solution than the default one, the click on "Add Domain" If you need an FTP account for that addon domain check the box "Create an FTP account associated with this Addon Domain." and fill the extra fields.