(also host name, nodename, computer name, site name)
In computer networking, a hostname is the label given to a device to identify it on a particular computer network. It can be freely selected by the host to organize devices by function — for example, “companymail” could denote the server responsible for handling the organization's email.
On the internet, hostnames are an integral part of the fully qualified domain name (FQDN) that maps devices in the Domain Name System (DNS). In addition to the hostname, FQDNs supply the required root labels, domain names, subdomain names, and other necessary information. The hostname is the left-most element of a FQDN — for example, “companyemail” is the hostname of the FQDN “companyemail.example.com.”