In computer networking, a hostname is a label that is used to identify a device. The hostname related to your HostGator package is essentially the name of your server (Dedicated or VPS). The primary function of the hostname is to establish a name for your server, from which preliminary DNS settings are generated, allowing the managed server to function. The hostname also serves as a public identifier for your server, documented in mail services and various DNS records, such as rDNS.
Due to the way cPanel handles naming, it is very important that your hostname not exactly match any domain you want to place on any account within the server. It is also strongly recommended that you do not include "www." in your server hostname, as cPanel uses this subdomain by default.
When you sign up for a VPS or Dedicated server package, your primary domain is used to create your hostname. By default, it is the first three letters of the domain name, followed by the domain and TLD. The hostname is often times compared to cPanel subdomains. However, it is only similar due to the style of the name itself.
Thus, if the package is ordered with the domain of myawesomeskills.ninja, then your hostname will likely be mya.myawesomeskills.ninja.
The following example will not work on your HostGator service:
cPanel domain: myawesomeskills.ninja
cPanel subdomain: dev.myawesomeskills.ninja
This example will not work because the subdomain matches the hostname, which cPanel does not allow.
The following example will work on your HostGator service:
cPanel domain: awesomeskills.ninja
cPanel subdomain: dev.awesomeskills.ninja