A network is a group of two and more computer system linked together.
There are many types of computer networks-:
1.Local Area Network (LAN)
2.Wide Area Network (WAN)
3.Campus Area Network (CAM)
4.Metropolitan Area Network (MAN)
5.Home Area Network (HAN)
6.Personal Area Network (PAN)
7.Virtual Private Network (VPN)
8.Storage Area Network (SAN)
9.Enterprise Private Network (EPN)
10.Wireless Local Area Network (WLAN) 
a network is a collection of two or more computer. they are linked each other.
there are mainly three types of computer lan (local area network) wan(wide area network) and third is man(metropolitan area network)
thanks :)