Network Principle Review

Question 1: What is network?
A network consists of several nodes and links connecting these nodes. We need to install a lot of software on the computer to complete information exchange between computers. Networks exist to facilitate information exchange.
Question 2: Network Development.
The first phase of the network is the point-to-point mode of ARPAnet, which is the core of the entire network. The disadvantage is that when the only core has a problem, the network will be paralyzed, this is not conducive to information exchange. As a result, Arpa began to study various network interconnection technologies. This is the prototype of the Internet. In 1983, the TCP/IP protocol was written as the standard protocol on ARPANET, so that all computers using the TCP/IP protocol can connect to the Internet.
The second stage features a three-level Internet. (Three-level network is the backbone network, Regional Network, Campus Network (or enterprise network ))
The third stage is to form an Internet with a multi-layer ISP structure. (The ISP applies for multiple IP addresses from the Internet management organization and has communication lines at the same time.) At this time, the Internet does not belong to a single organization, it is owned by countless ISPs in the world. In fact, no organization can completely eat the huge cake of the network)

Communication between computers: A process of host a communicates with another process on host B.