A network is a group of computer systems and other compunting hardware devices  that are linked together.
This is divided in three: LAN, MAN and WAN
>LAN: a computer network that can be conected ro other LANs over a distance
>MAN: a computer network that spans an entire city or campus
>WAN: a computer connection that exists over a large-scale geographical area
>WWW: a computer network online that have lots of every tipe of information