A host name is a name that is assigned to a host that uniquely identifies it on a network and thus allows it to be addressed without using its full IP address.
A host is a computer that is connected to a network, usually the Internet or other TCP/IP (transmission control protocol/Internet protocol) network, such as a LAN (local area network). Each host on a TCP/IP network has a unique IP address, which is a unique numeric identifier.
Host names are very useful because it is much easier for humans to remember them than to remember IP addresses, which can contain as many as 12 digits under the currently mainstream IPv4 addressing scheme (or as many as 32 hexadecimal digits under the next-generation IPv6 addressing scheme). Moreover, it is a simple matter for system administrators to assign host names on a LAN or other private network.
Host names on smaller networks typically consist of a single word (or words) that describe the host and omit the domain name. A domain name is a name that uniquely identifies a host on the Internet. For example, some of the computers in the accounting department of a small business might be assigned host names such as accounting1, accounting2 and accounting3.
Each host typically has a single host name. However, hosts are also allowed to have multiple host names.