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The **ARPANET** (**Advanced Research Projects Agency Network**) developed by [|ARPA] of the [|United States Department of Defense] during the [|Cold War], was the world's first operational [|packet switching] network, and the predecessor of the global [|Internet].

In 1966, the Advanced Research Projects Agency (ARPA) hosted a program with several research institutions called Resource Sharing Computer Networks. = =

**Goal:**
Was to link different [|computers] together, both to increase overall computer power and to decentralize information storage. =**// Purpose: //**= The U.S. government wanted to find a way to access and distribute information in the case of a catastrophic event, such as a nuclear attack. If a bomb hit an important computer line, information transfers would stop immediately. But if there were a way to [|network]  computers, other parts of the system could keep running even if one link were destroyed.

=** Phase 1: **= Four computer systems in different locations would link together using existing __[|phone]__ lines and four **Interface Message Processors** (**IMPs**). //Now called routers// []


 * [[image:1969_4-node_map.gif caption="4-node ARPANET diagram"]] ||
 * 4-node ARPANET diagram ||

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The initial ARPANET consisted of four IMPs. They were installed at: The first message ever to be sent over the ARPANET (sent over the first host-to-host connection) occurred at 10:30 PM on [|October 29], [|1969]. It was sent by UCLA student programmer Charley Kline and supervised by UCLA Professor Leonard Kleinrock. The message was sent from the UCLA SDS Sigma 7 Host computer to the SRI SDS 940 Host computer. The message itself was simply the word "login." The "l" and the "o" transmitted without problem but then the system crashed. Hence, the first message on the ARPANET was "lo". They were able to do the full login about an hour later.
 * [|UCLA], where [|Leonard Kleinrock] had established a Network Measurement Center (with an SDS Sigma 7 being the first computer attached to it).
 * The [|Stanford Research Institute]'s [|Augmentation Research Center], where [|Douglas Engelbart] had created the ground-breaking [|NLS]system, a very important early [|hypertext] system (with the [|SDS 940] that ran NLS, named 'Genie', being the first host attached).
 * [|UC Santa Barbara] (with the [|Culler]-Fried Interactive Mathematics Centre's [|IBM] [|360/75], running [|OS/MVT] being the machine attached).
 * The [|University of Utah]'s Computer Science Department, where [|Ivan Sutherland] had moved (for a [|DEC] [|PDP-10] running [|TENEX]).

The first permanent ARPANET link was established on [|November 21], [|1969] , between the IMP at UCLA and the IMP at SRI. By [|December 5], [|1969] , the entire 4-node network was connected.[|[4]] The contents of the first e-mail transmission (sent in [|1971]) have long since been forgotten; in an FAQ on his website, the sender, Ray Tomlinson (who sent the message between two computers located side-by-side) claims that the contents were 'entirely forgettable, and I have, therefore, forgotten them' and speculates that the message was most likely 'QWERTYUIOP' or something similar.[|[5]] [] 