This article is from the AmiTCP/IP FAQ, by Mike Meyer with numerous contributions by others.
An "internet" is a network comprised of computers that talk to each other using TCP/IP.
The "Internet" is a vast network of hundreds of thousands of machines using TCP/IP to communicate.
The Internet grew out of a US government funded project in inter-computer communications that grew into an enormous network of systems. One of the principle characteristics of this network is that machines are addressed by domain names which identify the destination, rather than addresses that are constructed out of the route from machine to machine to machine.
 
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