There are many types of networks. A telephone system is a network that carries voice signals. The Television is a network that carries video signals. Computers can be interconnected to form networks to carry data. Hence, computer networks are data communication networks. It is now possible to combine these technologies and a single network can be formed.

Computer networks share data, hardware and software. Basically, Private computer networks are of two types. LANS and WANS. The LAN is a local area network, linking computers from within a local area for example a single office or a Home. Lan interconnects computers within a single premises. But, if you connect two LANs over a substantial distance, you can do so by means of Long distance communication called WAN. So, if you want to interconnect your office LAN located at Philadelphia with the office LAN at Los Angeles than you have to interconnect the two LANS by specially dedicated telephone lines or satellite uplinks, and this form of network is called as WAN or "Wide area Network". 

Building small private LANs can bring in a lot of benefits now-a-days. With the help of a LAN you can work together on common projects or share costly peripherals with coworkers.Suppose you have Basic level computers in your house, one belonging to you, and others belonging your wife and parents. You also have Gaming Computers for your children.You can create a simple wireless  Home LAN by interconnecting all these computers using Window Xp. Now, you can share the computers and work together on a common project. You can now have only one printer instead of having many printers in your home, and share it among yourselves.

It is the same for your office LAN. Business PC's  can be interconnected to form a wireless Office LAN using Windows Xp operating sytem. Now, your office staff can easily communicate among themselves and share costly peripheral devices such as the printers etc. over the LAN network.