A computer network is a collection of two or more computers with communication between them through a medium. The communication medium can be through radio waves, wires, infrared, optical fibers etc.
Computer network is an integral part of our daily lives, with the most important reason being that of communication. The use of computer networking is to share resources like fax machines, printers, modems, files etc., and its other uses are database server, computer server, email, chat, internet etc. The computer to which the resources are attached is called the server and the other computers that access the resource are called clients. In peer-to-peer computer networks there are no servers.
The sharing of fax machines, printers, and modems amongst many computers and users reduce the operational cost. A database on a computer network is a very important application as it stores and runs many important data and jobs. Emails and chats can be used for instantaneous communication and sending of files on a computer network.
The computer networks are classified, depending upon the size, as Local Area Networks (LAN), Wide Area Networks (WAN), Metropolitan Area...