In computer networking, a hostname (archaically nodename) is a label that is assigned to a device connected to a computer network and that is used to identify the device in various forms of electronic communication, such as the World Wide Web.

Hostnames may be simple names consisting of a single word or phrase, or they may be structured.

Each hostname usually has at least one numeric network address associated with it for routing packets for performance and other reasons.

Internet hostnames may have appended the name of a Domain Name System (DNS) domain, separated from the host-specific label by a period ("dot").

In the latter form, a hostname is also called a domain name.

If the domain name is completely specified, including a top-level domain of the Internet, then the hostname is said to be a fully qualified domain name (FQDN).

Hostnames that include DNS domains are often stored in the Domain Name System together with the IP addresses of the host they represent for the purpose of mapping the hostname to an address, or the reverse process.

In the Internet, a hostname is a domain name assigned to a host computer.
This is usually a combination of the host's local name with its parent domain's name.
For example, consists of a local hostname (en) and the domain name
This kind of hostname is translated into an IP address via the local hosts file, or the Domain Name System (DNS) resolver.
It is possible for a single host computer to have several hostnames; but generally the operating system of the host prefers to have one hostname that the host uses for itself.

Any domain name can also be a hostname, as long as the restrictions mentioned below are followed.
So, for example, both and are hostnames because they both have IP addresses assigned to them.
A hostname may be a domain name, if it is properly organized into the domain name system.
A domain name may be a hostname if it has been assigned to an Internet host and associated with the host's IP address.