The Internet and Its Services
Working with Internet does not mean just browsing www and sending and receiving e-mails. The Basic Structure of the Internet was developed through last 30 years of existence of the Internet. The Internet is a heterogeneous worldwide network consisting of a large number of host computers and local area networks. The Internet uses the TCP/IP suite of protocols. This allows the integration of a large number of different computers into one single network with highly efficient communication between them. This way, the user can access information on all kinds of host computers from a desktop PC, Macintosh, or whatever he/she has available. TCP/IP, the communication standard underlying the Internet, originates from work done at the US-Department of Defense in the late 1960s. The first version of the Internet was built in 1969 and consisted of just four computers. In 1982 a set of specifications and protocols have been implemented, which became known as TCP/IP in reference to their two major elements, the "Transmission Control Protocol" and the "Internet Protocol". The development and implementation of TCP/IP stimulated a massive growth process for the Internet. "By late 1987 it was estimated that the growth had reached 15% per month and remained high for the following two years. By 1990, the connected Internet included over 3,000 active networks, over 3,000 active networks, and over 200,000 computers. By January 1992 the number of hosts on the Internet was 727,000, doubling about every 7 months. Various groups of users are connected to the Internet: universities and other educational institutions, government agencies, the military, and at an increasing number private businesses.
The most fundamental function of the Internet is to pass electronic information from one computer to another. A 32 bit Internet Address or IP-Number identifies every computer on the network. This number is commonly represented as four numbers joined by periods. The Internet uses these numbers to guide information through the network. This is called routing. For human users, however, such numbers are usually difficult to keep in mind. Therefore, computers are also identified by Domain Names, which are to some extent similar to mailing addresses. Special programs, called name servers, translate domain names into IP-Addresses. Internet services can be divided into two groups, communication services, and information services. In the first group, the Internet mediates in the communication between two or more individuals. In the second group, the user turns to the Internet-service in search for some particular information. Communication services can roughly be compared to a telephone call, information services to a dictionary .The most important communication services on the Internet are electronic mail, Netnews and some derived services. Major information services are terminal emulation and file transfer, Gopher, WAIS, and World Wide Web.