The development of computer network has gone through several stages.

It has gone through three stages, as follows:

1, the first stage (early 1960s to mid 1960s). A computer communication network is characterized in that computers and terminals are interconnected to realize remote access. The first generation computer network consists of host, communication lines and terminals, which can only be regarded as the embryonic form of computer network.

In the first stage, the single computer network system with remote communication function solved the problem of multi-user sharing host resources. The terminal is a dumb terminal, without its own CPU, memory and hard disk, and has no ability. Existing problems: heavy host burden and high communication cost. It also has a multi-machine system with remote communication function, which solves the problems of heavy host burden and expensive communication cost. Problem: Multiple users can only * * enjoy one host resource.

2. The second stage (from the mid-1960s to the mid-1970s): the communication between computers was realized by using packet switching technology, which changed the structure and concept of computer network and formed the network structure of communication subnet and resource subnet. The second generation computer network is the "formation and development" stage of computer network; ARPA network in America is the representative of the second generation network. The main problem is that the network is opaque to users.

3. The third stage (from the mid-1970s to the late 1980s): the interconnection stage of modern computer networks, characterized by the formation of network architecture and the standardization of network protocols.

On the basis of computer communication system, we attach importance to the study of network architecture and protocol standardization, establish unified communication rules for the whole network, use communication protocol software to realize intra-network and inter-network communication, and manage network resources through network operating system, which greatly simplifies the use of users and makes computer networks provide transparent services for users.