In English, "Inter" means "interaction" and "net" means "network". Simply put, the Internet is a computer interactive network, also known as the Internet. It is a huge global computer network system, connecting tens of thousands of computer networks and tens of millions of hosts around the world, containing countless information resources and providing information services for the whole world. Its appearance is the inevitable sign of the world's transition from industrialization to informationization, but this is not a definition of the Internet, but only an explanation. From the perspective of network communication, Internet is a data communication network that connects computer networks of various countries, regions and institutions with TCP/IP network protocol. From the perspective of information resources, the Internet is an information resource network that integrates various information resources from various departments and fields for Internet users to enjoy. Today's Internet has gone far beyond the meaning of a network, and it is the epitome of an information society. Although there is no accurate definition to summarize the Internet, this definition should be comprehensively considered from the perspectives of communication protocol, physical connection, resource sharing and interconnection. It is generally believed that the definition of the Internet includes at least the following three aspects:
Internet is based on TCP/IP protocol family.
Internet is a group of network users who use network resources and contribute to network development.
Internet is a collection of all information resources that can be accessed and utilized.
The History and Development of Internet
Internet originated from ARPAnet established by ARPA, the predecessor of DARPA, and was put into use in 1969. Since 1960s, ARPA has been providing funds to computer departments of American universities and some private limited companies to promote the research of computer networks based on packet switching technology. 1968, ARPA established the ARPAnet network project. The leading idea of this project is that the network must be able to withstand the test of failure and keep working normally. In the case of war, when a part of the network loses its working ability due to an attack, other parts of the network should be able to maintain normal communication. Initially, ARPAnet was mainly used for military research purposes, and it has five characteristics:
(1) Support resources * * *;
⑵ Using distributed control technology;
(3) adopting packet switching technology;
(4) using a communication control processor;
5] Using layered network communication protocol.
1972, ARPAnet first met with the public at the first international conference on computer background communication, which verified the feasibility of packet switching technology. Therefore, ARPANET has become the symbol of the birth of modern computer networks.
Another important contribution of ARPAnet in technology is the development and use of TCP/IP protocol family. 1980, ARPA invested in adding TCP/IP to the kernel of UNIX (BSD version 4. 1). After BSD version 4.2, TCP/IP protocol became the standard communication module of UNIX operating system. 1982, the internet was formed by the merger of ARPAnet, MILNET and other computer networks. ARPAnet, as the early backbone network of the Internet, tested and laid the foundation for the existence and development of the Internet, and solved a series of theoretical and technical problems in the interconnection of heterogeneous computer networks.
1983, ARPAnet was split into two parts: ARPAnet and MILNET, which were purely military. In June, 5438+that year 10, ARPA took TCP/IP protocol as the standard protocol of ARPAnet. Later, people called the Internet with ARPAnet as the backbone network, and the TCP/IP protocol family was studied and tested in the Internet and improved into a convenient and efficient protocol family.
At the same time, the emergence and vigorous development of local area network and other wide area networks have played an important role in the further development of the Internet. One of the most striking is the National Science Foundation Network NSFnet (1986) established by the National Science Foundation of the United States. In order to make scientists and engineers all over the country enjoy these supercomputer facilities, NSF has established its own computer network NSFnet based on TCP/IP protocol suite. NSF has established computer wide area networks divided by regions throughout the country, and connected these regional networks with supercomputing centers, and finally interconnected supercomputing centers. The composition of a local area network is generally composed of a group of computers that are geographically confined to a certain area, belong to an organization in management or have the same interests in economy. The high-speed data line connecting the computers of the main communication nodes on the local area network constitutes the backbone network of NSFnet. In this way, when a user's computer is connected to a certain area, he can not only use the facilities of any supercomputer center, but also communicate with any user on the network to obtain the network. This success enabled NSFnet to completely replace ARPAnet and become the backbone of the Internet in June 1990.
NSFnet's greatest contribution to the Internet is to make the Internet open to the whole society, instead of being used only by computer researchers, government employees and government contractors as before. However, with the rapid growth of online traffic, NSF has to adopt newer network technology to meet the needs of development. 1September, 990, Merit, IBM and MCI jointly established a non-profit organization-Advanced Network and Science Company ANS(Advanced Network & amp； The purpose of. ANS is to build a T3 backbone network in the United States, which can transmit data at a rate of 45Mb/s, which is equivalent to transmitting 1400 pages of text information per second. As of 199 1, all backbone networks of NSFnet have been connected with T3 backbone network provided by ANS.
1969 65438+February, when ARPAnet was first built, there were only four nodes; By March 1972, there were only 23 nodes; By March 1977, there were only 1 1 nodes. However, in recent ten years, with the development of social science, technology, culture and economy, especially the great development of computer network technology and communication technology, the trend of human society's transition from industrial society to information society has become more and more obvious, and people's information awareness and emphasis on the development and utilization of information resources have strengthened, which has effectively stimulated the development of ARPAnet and NSFnet. The number of hosts and users connected to these two networks has increased dramatically. 1988, the number of computers connected to NSFnet soared to 56,000, and then it developed at an amazing speed of 2 to 3 times every year. 1994, the number of hosts on the internet reached 3.2 million, connecting 35,000 computer networks in the world. At present, there are more than 50 million Internet users, and the number is increasing at the rate of 10- 15% every month. Experts predict that by 1998, the number of Internet users will exceed 100 billion, and by 2000, there will be more than 100 billion networks in the world. Today's Internet is no longer a field for computer personnel and military departments to conduct scientific research, but a global information ocean for developing and utilizing information resources. On the Internet, there are more than 65,438+000 kinds of businesses, including advertising companies, airlines, agricultural production companies, arts, navigation equipment, bookstores, chemicals, communications, computers, consulting, entertainment, finance and trade, various shops, hotels and so on, covering all aspects of social life and forming a microcosm of an information society.
As early as 1987, the Institute of High Energy Physics of the Chinese Academy of Sciences first realized international long-distance networking through X.25 leased lines, and realized e-mail communication with Europe and North America in 1988. 1in March, 1993, with the strong cooperation of the telecommunications department, a special high-speed computer communication line was opened from Beijing Institute of High Energy to Stanford Linear Acceleration Center in the United States. 1in may, 1994, the computer of the institute of high energy physics was officially connected to the internet. At the same time, Tsinghua University-centered China Education and Research Network was officially connected to the Internet in June, 1994. In June, CHINAnet, the largest Internet subnet in China, was officially opened and put into operation. There is an upsurge of research, study and use of the Internet in China. More and more users in China have access to the Internet, and the Internet has increasingly become an important part of people's scientific research and daily life in China.
Internet originated from 1969. At that time, the Advanced Research Projects Agency (ARPA) of the US Department of Defense established an experimental packet switching network ARPAnet, which was composed of four computers, in order to ensure the communication within the military when nuclear war broke out. At that time, the goal of ARPAnet plan was to establish a fast and convenient network, so that independent computers of the US military could transmit information and data to each other, and they could still handle and recover faults themselves in various complicated situations such as power failure, line interruption and even nuclear attack, thus ensuring the stability and reliability of data communication. 1976, the number of node computers on ARPAnet has increased to 57, connecting more than 100 computers and more than 2000 networked users. At this time, ARPA began to convene researchers who participated in ARPAnet research and held some informal meetings to discuss related technical issues. 1979, ARPA established an informal committee ICCB (Internet Control and Configuration Committee) to coordinate and guide the design of Internet protocols and architectures. The new network protocol is named TCP/IP, which is called Transmission Control Protocol/Internet Protocol in English, that is, Transmission Control Protocol/Internet Protocol. At this time, the word Internet officially appeared.
1980, ARPA began to switch computers running on ARPAnet to the new TCP/IP protocol. 1982, the U.S. Department of Defense ordered that the networks connected to ARPAnet must be interconnected by IP protocol (that is, Internet protocol). Moreover, this transformation was completed in 1983, which is why the Internet is called the Internet. In the same year, DCA divided ARPAnet into two independent networks: one is still called ARPAnet (for further research); One is called MILnet (for military communication).
The success of ARPAnet network and TCP/IP technology makes the National Science Foundation realize that the network will become an important means of scientific research. In order to enable researchers to enjoy the supercomputing facilities provided by the military for only a few people in the past, NSF established five supercomputing centers in the United States on 1985, and established a high-speed information network named NSFnet on 1986. The network connects all the supercomputers of NSF and ARPAnet. In this way, NSFnet replaced ARPAnet and became the backbone of the Internet. NSFnet also adopts TCP/IP protocol, and NSFnet is open to the whole society, which makes the Internet enter a practical service stage centered on resource enjoyment. Since then, the Internet has developed rapidly and soon spread to the whole world.