Today networks can be divided into three broad categories:
LANs (Local Area Networks)
MANs (Metropolitan Area Networks)
WANs (Wide Area Networks)
The category that a network falls into is determined by its size. A LAN normally covers a small area, a WAN can be worldwide, and a MAN covers a small city or town.
LAN (Local Area Network)
A LAN, is a network of connected computers and other devices at a single location. A school or an office building that has all of its computers connected together to share data and printers is a common example of a LAN.
MAN (Metropolitan Area Network)
A MAN, is a network with a size between a LAN and a WAN. It normally covers the area inside a town or a city. It is designed for customers who need high-speed connectivity, usually to the Internet. A good example of a MAN is that part of a telephone company's network that provides a high speed DSL line to the customer.
WAN (Wide Area Network)
A WAN, as the name implies, is a network of connected computers and other devices that are spread out over a large geographic location. The greatest example of this is The Internet. The internet is the worlds largest WAN spreading around the globe and connecting millions of computers and devices. A WAN is essentially a group of LANs connected together over a larger area.