Computer network technology is the product of the combination of communication technology and computer technology. Computer network is a system that connects scattered and independent computers on earth to realize resource sharing and information transmission according to network protocol. The connecting medium may be a cable, twisted pair, optical fiber, microwave, carrier, or communication satellite. Computer network has the function of sharing hardware, software and data resources, and has the ability to process and manage and maintain the shared data resources centrally. Generally, according to the network scope, it is divided into LAN, man and WAN.
Computer network includes two parts: computer and network. Computer is also called electronic computer, commonly known as computer, which is a modern intelligent electronic equipment which can automatically and rapidly process massive data according to the program. A computer consisting of hardware and software and without any software is called a bare metal. The common forms are desktop computer, notebook computer, large computer, etc. The more advanced computers include biological computer, photon computer, quantum computer, etc. The network is to connect each isolated workstation or host with physical link to form data link, so as to achieve the purpose of resource sharing and communication. Therefore, computer network refers to the system that connects multiple autonomous computer systems and their external networks with different geographical locations through communication media, and realizes resource sharing and information transmission under the management and coordination of network operating system, network management software and communication protocol.
Computer network can be classified according to different standards such as network topology, network scope and interconnection distance, network data transmission, owner of network system, different service objects, etc. Generally, it is divided into three parts: network scope:
(3) Wide area network (WAN). The geographical range of LAN is generally within 10 kilometers, and belongs to a small network formed by a department or group of groups, such as a school, a unit or a system. Wan covers a wide range of areas, ranging from dozens of kilometers to tens of thousands of kilometers. For example, a city, a country or an intercontinental network, at this time, transmission devices and media for communication are generally provided by the telecommunication department, which can realize a large range of resource sharing. Man is between LAN and WAN, which usually covers a city or region, from dozens of kilometers to hundreds of kilometers.