WAN

Covers a wide geographical area, often include state or
continents. WAN consists of a collection of machines that aim to run
programs (applications) user. This machine is called HOST. HOST
connected by a communication subnet or subnet is called.
Subnet is the task of carrying messages from one host to another host. In the
most of the WAN subnet consists of 2 components: cables and transmission
switching element.
Router
HOST
LAN
Subnet
Relationship between host-host with a subnet