What is computer Network?

A computer network is a group of interconnected computers which able to communicate to each other.

Networking is the practice of linking two or more computing devices together for the purpose of sharing data. Networks are built with a mix of computer hardware and computer software.

Most networks use electrical wires of some special kind to convey signals and data between computers. However, numerous types of networking media, including wireless broadcast technologies and fiber optic cables can support networked connection as well. In other words, you can get from here to there in many ways on modern networks.

The basic computer network hardware for example are NIC (network interface card),repeater, hub, switch, and router.
To make computer can communicate to another, we need some protocols.

Let's see how a computer connect to another in a simple delineation.

on above figure, two computer are connected with a transmission line, e.g a cable.
the red line on that figure is represent two wire which actually connect the two of them using NIC.

See, the transmit line of the first computer connected to receive line on other computer.