In its most basic form, a network is two or more computers that are connected with a communications line for purposes of sharing resources. A basic network that connects Tom's PC to Sally's PC so that they can share each other's files. So, if two (or more) computers connect to each other over a telephone line or through a piece of cable or even through a wireless connection and the users are able to access ad share files and peripheral devices on the other computers, a network is formed. Most networks are a little more complicated than this, but essentially the arrangement just described is all that is really necessary.
As you might guess, there are different levels and types of networks. Networks are classified by the size and scope of the area they serve. The most common classifications for networks are as follows:
Local area network (LAN) Usually computers connected to a network that is confined to a single office or building. The network in an office or a school's computer lab is typically a LAN.
Campus area network (CAN) A variation of a LAN that extends to include computers in buildings that are in close proximity to one another, such as in an office park or campus setting. The network that connects the buildings of a college or a manufacturing company's buildings is an example of a CAN.
Wide area network (WAN) Interconnects LANs and computers that are located over a large geographical area. Typically, the WAN is built on dedicated high speed communications lines. The big WAN is the Internet, which is actually a network of networks (something called a nexus), but the network that connects the New York office of a company to its plant in Washington State is also a WAN.
Metropolitan area network (MAN) A type of WAN that interconnects LANs and computers within a specific geographical area, such as a city or a cluster of campuses or office parks. Several cities, including Cleveland, Chicago, and Spokane, have established MANs to provide connectivity to downtown businesses.
