The collection of interconnected networks is the Internet (in English, Internet), which refers to the specific global Internet.

Internal network

Intranet is a network based on TCP/IP protocol family belonging to an organization (such as a company). Only members of the organization (such as company employees) and authenticated users can access the intranet. From the technical and formal point of view, intranet and Internet are similar.

Firewall is a system to prevent unauthenticated information from entering or leaving the private network, which can be realized by hardware or software, or by a combination of the two. Generally, firewall is located between private network (intranet) and external network (Internet), which is the only entrance and exit of information between networks.

extranet

The extranet is actually an extension of the intranet. Extranet not only allows people inside the organization to access, but also allows authorized outsiders to access some of its resources.

We'd better not use the word Internet to express this word. Internet is a collection of international communication networks that combines modern communication technology and modern computer technology. It is a good means for international information exchange and resource sharing between computers.

Internet connects all kinds of physical networks to form a whole, regardless of the similarities and differences, size and geographical differences of these network types, so the accurate description is: Internet is a network of networks.

Internet developed from the early APRANET network, and the research on packet switching technology and network interconnection technology on APRANET led to the emergence and development of TCP/IP. The TCP/IP protocol adopted by the Internet is a connectionless end-to-end communication protocol, which is simple and practical and can ensure users to do it at the application layer. At present, TCP/IP is widely used, not only for mainframes, but also for minicomputers and PCs, as well as for local area networks and wide area networks. In principle, any computer can access the Internet according to certain rules as long as it abides by the TCP/IP protocol.

1982, with the support of ARPA, the University of California at Berkeley embedded the TCP/IP protocol into UNIX BSD 4. 1, which greatly promoted the application process of TCP/IP.

1983, TCP/IP became the standard communication protocol on APRANET, marking the emergence of the real Internet.

1986 With the support of the U.S. government, the National Science Foundation of the United States leased the communication lines of telecommunications companies to form a new Internet backbone network, the National Science Foundation Network (NSFNET), which was used to connect the six supercomputer centers at that time with universities and academic institutions in the United States.

1989, ARPANET was dissolved, and NSFNET was opened to the public, becoming the most important communication backbone network of the Internet.

1992 65438+ 10, Internet Association (ISOC) came into being due to the sharp increase in the number of Internet users, the increasing number of internet organizations and the gradual expansion of application fields. It is an organization formed spontaneously by users, and its goal is to formulate Internet-related standards and popularize the Internet. At the same time, the commercial and communication industries have begun to attach importance to the Internet, and the voice of Internet commercialization is getting higher and higher.

1995, the National Foundation of the United States announced the plan to cooperate with MCI to build a high-speed data channel, and provide 155Mb/s ultra-high-speed backbone network service (vBNS) to replace the existing NSFNET. Major communication companies also announced their own Internet interconnection plans. The internet age came from this.