What Counts as a "Fully Qualified" Domain Name?

A fully qualified domain name (FQDN) provides the full address for a device that is connected to the internet such as a website or server.

It consists of a hostname, a second level domain, and top level domain.

Importantly, it has a dot or period at the end.

The FQDN for this site is www.dominion.domains. (note the trailing period).