A subject related to hosts are subdomains.
DNS works in a hierarchy. TLDs can have many domains under them. For instance, the "com" TLD has both "google.com" and "ubuntu.com" underneath it. A "subdomain" refers to any domain that is part of a larger domain. In this case, "ubuntu.com" can be said to be a subdomain of "com". This is typically just called the domain or the "ubuntu" portion is called a SLD, which means second level domain.
Likewise, each domain can control "subdomains" that are located under it. This is usually what we mean by subdomains. For instance you could have a subdomain for the history department of your school at "www.history.school.edu". The "history" portion is a subdomain.
The difference between a host name and a subdomain is that a host defines a computer or resource, while a subdomain extends the parent domain. It is a method of subdividing the domain itself.
Whether talking about subdomains or hosts, you can begin to see that the left-most portions of a domain are the most specific. This is how DNS works: from most to least specific as you read from left-to-right.
Alert: For Control Panel Help & Tutorials, click here: Panel Tutorials
