How to add an “addon domain” at Bluehost
Most webmasters own more than one domain/website.

However, we do not need multiple hosting for those domains.
Most hosting plan available online enable webmaster to host multiple domain on a same hosting account – Bluehost for example, allows their clients to host unlimited addon domain on one single hosting account.
We’ll see how to add an ‘addon domain’ at Bluehost in this post. But first, we have to be very clear on the difference between an ‘addon domain’ and a ’subdomain’.
Addon Domain vs Subdomain
What’s an ‘addon domain’?
An ‘addon domain’ is a new domain that’s added on top of your main domain.
For example if you purchase Bluehost hosting package now to host your website abcd.com; abcd.com is your main domain. 6 months later you decided to register another domain name with GoDaddy, say efgh.com, and wanted to host it on the same Bluehost account, then efgh.com is the ‘addon domain’ that’s added on top of abcd.com.
Setting up an ‘addon domain’ will not create you another cPanel (web hosting manager) at Bluehost. However, it will creates a sub directory in your main web hosting directory and the addon domain website will have it’s very own index files as well as cgi bin folder.
What’s a ’subdomain’?
Quoting from Wikipedia, a subdomain is a domain that is part of a larger domain. For example, “mail.example.com” and “calendar.example.com” are subdomains of the “example.com” domain, which in turn is a subdomain of the “com” top-level domain.
A very important point to keep in mind is that unlike addon domian, subdomains are free of charge at Bluehost. It can be created at will for any domain you already hosted with Bluehost. Like for our previous example, you can create a subdomain named ‘efgh.abcd.com’ without paying any registration or annual maintenance fees.
How to add an “addon domain” at Bluehost?

Go to the ‘Domain’ section and click ‘Addon Domains’ on your Bluehost cPanel page.
Note that you can as well register a new domain name, park a domain, add a subdomain, setup a redirect for your domain on the same section. But for our discussion, we’ll limit the topic within the addon domain.

You’ll be requested to login to Bluehost Domain Manager after that. Once you’re in, you’ll come to a setup page where you’ll need to keyin all the necessary info about your addon domain.
The input fields, like the domain name, the location of your website folder, and so on are pretty basics and I am sure you can handle it without my guidance.
However, one thing to be sure is that you MUST have your domain name server pointing to Bluehost’s server before you adding any addon domain in your hosting account. This is crucial for Bluehost to verify your ownership of the domain and Bluehost will not process your request (of adding an addon domain) without it.