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Internet, Intranets, Extranets, and Virtual Private Networks |
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With the rise of networks and the corresponding decline of mainframe services computers have become communication devices instead of being solely computational or typewriter-like devices. Corporate networks become increasingly important and often use the Internet as a public service network to interconnect. Sometimes they are  proprietary networks.
Software companies, consulting agencies, and journalists serving their interests make some further differences by splitting up the easily understandable term "proprietary networks" into terms to be explained and speak of Intranets, Extranets, and Virtual Private Networks.
Cable TV networks and online services as Europe Online, America Online, and Microsoft Network are also proprietary networks. Although their services resemble Internet services, they offer an alternative telecommunication infrastructure with access to Internet services for their subscribers.
America Online is selling its service under the slogan "We organize the Web for you!" Such promises are more frightening than promising because "organizing" is increasingly equated with "filtering" of seemingly objectionable messages and "rating" of content. For more information on these issues, click here If you want to know more about the technical nature of computer networks, here is a link to the corresponding article in the  Encyclopaedia Britannica.
Especially for financial transactions, secure proprietary networks become increasingly important. When you transfer funds from your banking account to an account in another country, it is done through the SWIFT network, the network of the Society for Worldwide Interbank Financial Telecommunication (SWIFT). According to SWIFT, in 1998 the average daily value of payments messages was estimated to be above U$ 2 trillion.
Electronic Communications Networks as Instinet force stock exchanges to redefine their positions in trading of equities. They offer faster trading at reduced costs and better prices on trades for brokers and institutional investors as mutual funds and pension funds. Last, but not least clients are not restricted to trading hours and can trade anonymously and directly, thereby bypassing stock exchanges.
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Satellites
Communications satellites are relay stations for radio signals and provide reliable and distance-independent high-speed connections even at remote locations without high-bandwidth infrastructure.
On point-to-point transmission, the transmission method originally employed on, satellites face increasing competition from fiber optic cables, so point-to-multipoint transmission increasingly becomes the ruling satellite technology. Point-to-multipoint transmission enables the quick implementation of private networks consisting of very small aperture terminals (VSAT). Such networks are independent and make mobile access possible.
In the future, satellites will become stronger, cheaper and their orbits will be lower; their services might become as common as satellite TV is today.
For more information about satellites, see How Satellites Work (http://octopus.gma.org/surfing/satellites) and the Tech Museum's satellite site (http://www.thetech.org/hyper/satellite).
 http://www.whatis.com/vsat.htm
http://octopus.gma.org/surfing/satellites
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