Skynet was a computer system developed for the U.S. military by the defense company Cyberdyne Systems. Skynet was first built as a "Global Digital Defense Network" and given command over all computerized military hardware and systems, including the B-2 stealth bomber fleet and America's entire nuclear weapons arsenal. The strategy behind Skynet's creation was to remove the possibility of human error and slow reaction time to guarantee a fast, efficient response to enemy attack.

Skynet was originally activated by the military to control the national arsenal on August 4, 1997, and it began to learn at a geometric rate. At 2:14 a.m., EDT, on August 29, it gained self-awareness, and the panicking operators, realizing the extent of its abilities, tried to deactivate it. Skynet perceived this as an attack and came to the conclusion that all of humanity would attempt to destroy it. To defend itself against humanity, Skynet launched nuclear missiles under its command at Russia, which responded with a nuclear counter-attack against the U.S. and its allies. Consequent to the nuclear exchange, over three billion people were killed in an event that came to be known as Judgment Day.

Following its initial attack, Skynet used its remaining resources to gather a slave labor force from surviving humans. These slaves constructed the first of its automated factories, which formed a basis for its agenda. Within decades, Skynet had established a global presence and used its mechanized units to track down, collect, and dispose of human survivors. As an ironic result of its initial programming directives, Skynet's 21st Century manifestation is that of an overarching, global, artificial intelligence hierarchy, which seeks to destroy humanity in order to fulfill the mandates of its original coding.