Computer network is a product of the combination of modern communication and computer technology. So-called computer network is distributed in different geographic areas of computers and dedicated communication lines for external devices connected into a large, powerful network systems, so that a large number of computers makes it easy to pass information to each other, shared resources such as hardware, software, data and information. Popular, network is cable, telephone line, or wireless communication, collection of interconnected computers.
Networks function through the network, to connect you and other users on a network to share network resources, such as files on a disk and a printer, modem, and so on, and they can also exchange information with each other.
According to the area of computer networking, we can divide the network into the LAN (LAN,Local Area Network) and Wan (WAN,Wide Area Network). Local area network (LAN) is a small computer network devices used within the geographical boundaries of communication network of interconnected together, can contain one or more subnets, usually confined to ranges of thousands of meters. Such as a room or a building, or on a campus network is called a local area network, wide area network (WAN) connections larger geographical areas, is often a country or a continent. The purpose of which is to enable the distribution of distant LAN interconnect. We usually talk about the Internet which is the largest and most typical wide area network.