What's the difference between a host name, a domain name and a fully qualified domain name (FDQN)?

What's the difference between a host name, a domain name and a fully qualified domain name (FQDN)?

A fully qualified domain name (FQDN) contains both a host name and a domain name. For a landing page, the fully qualified domain name usually represents the full URL or a major portion of the top-level address.

In looking at a fully qualified domain name, the host name typically comes before the domain name. The host name represents the network or system used to deliver a user to a certain address or location. The domain name represents the site or project that the user is accessing.

One example is the use of various networks to access educational websites. Typically, the domain name will consist of the identifier for a specific school’s web domain, along with the top-level .edu suffix. For example, the domain name for America University would be americauniversity.edu. The host name would consist of either "www" where the global internet is the host, or some proprietary network name that represents the host – for example, if the school uses a custom internal network called "myAUnet" then "myAUnet" would be the host name.

In connecting to a host, using the fully qualified domain name shows where the user wants to go. A DNS server can resolve the host name to an IP address. Although there is some syntactical tolerance built into the use of a fully qualified domain name, generally, a user can have errors or problems if the domain name is not clearly and completely entered.