What is a subdomain or subdomain?
A subdomain is a domain name that is formed from a top-level domain zone and an additional domain separated by a period. For example: support.goodhoster.net is a subdomain for goodhoster.net, in turn, goodhoster.net is a subdomain for the net domain. You have a domain name, for example: goodhoster.net, if you add any other domain to it (for example, support or 123best), you will get a subdomain support.goodhoster.net 123best.goodhoster.net and so on.
A parked domain is an additional domain name that is assigned to your website, an additional web address for your website. For example, you have one domain name that is attached to your website. Then you purchase another, second domain name and want your site to be accessible at both the first and the second address. Then, you simply add the second domain through the control panel as a parked domain and both domains will show the same site.
An “addon domain” is an additional domain name with a separate site on your account. You have one site on your account and you want to host another separate site - add a new domain name as an additional domain in the Cpanel control panel, creating a separate folder for the second site and a separate FTP account for uploading files of the new site. In the description of shared hosting plans, the number of additional domains or addon domains shows how many additional separate sites you can host in one account.