Telecommunication networks are transmission systems enabling information to be transmitted in analogue or digital form between various different sites by means of electromagnetic or optical signals.
The information may consist of audio/video data or some other types of data.
The networks are based either on wired or wireless infrastructures. Typical examples of telecommunication networks are the landline network, the mobile network, cable TV networks and the internet.
When several users of telecommunications media wish to communicate with one another, they must be organized into some form of network. Modern telecommunications networks avoid issues by establishing a linked network of switches, or nodes, such that each user is connected to one of the nodes.
Each link in such a network is called a communications channel. Wire, fibre-optic cable, and radio waves may be used for different communications channels.