The
Advanced Research Projects Agency Network (
ARPANET), was the world's first operational
packet switching network and the core network of a set that came to compose the global
Internet. The network was created by a small research team at the
Massachusetts Institute of Technology and the Defense Advanced Research Projects Agency (
DARPA) of the
United States Department of Defense. The packet switching of the ARPANET was based on designs by
Lawrence Roberts of the
Lincoln Laboratory.
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Packet switching, today the dominant basis for data communications worldwide, was a new concept at the time of the conception of the ARPANET. Data communications had been based on the idea of
circuit switching, as in the traditional telephone circuit, wherein a telephone call reserves a dedicated circuit for the duration of the communication session and communication is possible only between the two parties interconnected.
With packet switching, a data system could use one communications link to communicate with more than one machine by collecting data into
datagrams and transmit these as
packets onto the attached network link, whenever the link is not in use. Thus, not only could the link be shared, much as a single
post box can be used to post letters to different destinations, but each packet could be routed independently of other packets.