What is the difference between the following networks : VPN, WAN, LAN, MAN, SAN

Networks can be classified into different types:

VPN: Virtual private network, is a network that is constructed by using public wires — usually the Internet - - to connect to a private network, such as a company's internal network. There are a number of systems that enable you to create networks using the 

Internet as the medium for transporting data. These systems use encryption and other security mechanisms to ensure that only authorized users can access the network and that the data cannot be intercepted.

LAN:Is Local Area Networks cover a small physical area, like a home, office,colleges,airport.

WAN: Is Wide Area Networks which cover a larger geographical area than LAN. MAN are used in cases where communication links that cross metropolitan, regional, or national boundaries. The Internet is the best example of a WAN.

MAN: Is Metropolitan Area Networks are very large networks which cover an entire city.

SAN: Is Storage Area Networks which assist in connection or attachment of remote computer storage devices, such as disk arrays, tape libraries, and optical jukeboxes, to servers in such a manner that that they appear to be locally attached to the operating system.