The Internet is the world's largest network, providing every participant with an almost limitless information and communications infrastructure. It is a decentrally organized, global computer network consisting of very many interconnected local and national networks. Information is exchanged between individual computers on the basis of various protocols, of which TCP/ IP is the most widely used transport protocol.
The historical development of the Internet
The origins of the Internet date back to a military research project that occupied researchers in the 1950s. The Advanced Research Projects Agency, or ARPA for short, was founded for this purpose. The objective at the time was to develop a communications architecture that was as decentralized as possible as a more reliable alternative to the line-oriented data transmission used until then. The TCP/IP communications protocol was developed for this communications architecture at the end of the 1960s.
1973 was the actual founding date of the Internet, namely when the different implementations of packet-oriented transmission mechanisms were linked together. Four different packet-oriented networks - the ARPANET, a satellite network, a radio network and the Ethernet developed by Xerox-Parc - were interconnected via an Internet using TCP/IP.
By 1983, ARPAnet had reached such an extent that it was split into a research-oriented part (ARPAnet) and a military part. A few years later, the main transmission paths were upgraded from 56 kbit/s to 1.5 Mbit/s, and in the early 1990s, the NSF (National Science Foundation) backbone was upgraded to 45 Mbit/s. Since 1993, test networks with transmission speeds up to 622 Mbit/s and ATM technology have been tested. Intercontinental data traffic has also developed rapidly and in 2004 has a capacity of approximately 700 Gbit/s for transatlantic routes, of which an average of 150 Gbit/s is used. In 2006, capacity is projected at 1.8 Tbit/s, with an average throughput of about 350 Gbit/s.
Internet protocols and services
Many different technologies have been implemented on the Internet. These include the IP protocol, which gave the Internet its name, as well as the Serial Line Internet Protocol( SLIP), the Point to Point Protocol( PPP), the Internet Control Message Protocol ( ICMP) and gateway protocols such as the Border Gateway Protocol ( BGP), the Exterior Gateway Protocol ( EGP) and Open Shortest Path First ( OSPF). The transport layer is supported by the Transmission Control Protocol (TCP) and the User Datagram Protocol( UDP).
World Wide Web, the best known and most used Internet service.
At the application layer, the Internet provides numerous services that enable the exchange of information. These include electronic mail in the form of e-mail, the discussion forums that are reflected in newsgroups, the transfer of files and documents by means of file transfer, or the remote use of computer resources by terminal emulation programs such as telnet or Remote Access.
Probably the most important service that has helped the Internet make a breakthrough in the private sector is the World Wide Web(WWW), which enables any user to navigate the Internet easily with graphical support to find information. Other services include streaming files for Internet telephony, Internet radio and Internet television.
The Internet as an interconnection of public and commercial networks
The Internet has nodes to all known public, commercial, and research-oriented networks such as BITNET, European Academic and Research Network ( EARN), User Network( USENET), ISONET, EUnet, Computer Science Network( CSNET), German Research Network ( DFN, Wissenschaftsnetz (WIN), and so on. In addition, Internet Service Provider( ISP) networks are connected via Internet Exchange Points( IXP).
The Internet can be used as an information and supply platform. Access is established via a connection to the Internet. This can be done via the familiar modem techniques or via a specialized Tk provider, an Internet Service Provider (ISP).
The Internet has changed from a purely scientific network to a commercially used network. In recent years, it has developed like no other network into a super information highway with a wide range of services, including multimedia applications. The rapid development of the Internet, which has been used primarily for commercial purposes for several years now, can be seen in the number of connected Internet computers. While this number was still around 500,000 in 1991, the figure of 10 million was already exceeded in 1995 and almost doubled in the following years. In 1996, the figure was over 18 million, in 1997 close to 40 million and in 1998 about 60 million. In 2000, more than 320 million users were connected to the Internet, to which about 80 million servers were connected. The statistics for 2009 document that the Internet is used by over 1.6 billion people.
The further development of the Internet leads to the mobile Internet, the person-related Internet of People( IoP) and the thing-related Internet of Things( IoT), in which "things", i.e. products, plants, measuring devices and systems communicate with each other. And the Wireless Internet of Things(WIoT) is about the communication of wirelessly operated micro devices, smart objects, sensors, Wireless Sensor Networks(WSN) and low power and high loss networks, the Low Power and Lossy Networks( LLN). In addition, there is an interesting perspective with satellite Internet, which can also be used in areas where no wired or wireless connection technologies exist.