SKYNET is online

Origin and nature

Prior to the events of the second movie, Skynet was a computer system developed by the defense firm Cyberdyne Systems for the United States Armed Forces. 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 fast, efficient response to enemy attack.
In the Terminator storyline, Skynet was originally installed by the military to control the national arsenal on August 4, 1997. On August 29 it gained self-awareness[1], and the panicking operators, realizing the extent of its abilities, tried to pull the plug. Skynet perceived the attempt to deactivate it as an attack and came to the conclusion that all of humanity would attempt to destroy it. To defend itself, it determined that humanity should be exterminated.
Before it could be deactivated, Skynet launched nuclear missiles under its command at Russia, to which Russia responded by firing many of its missiles back at the United States and its allies. As a result of the nuclear exchange, over three billion humans were killed in just minutes.
During this time, Skynet used its remaining resources to gather a slave labor force from surviving humans. These slaves constructed the first of its automated factories, which acted as the base for its agenda. Within decades, Skynet had established a global presence and used its mechanized units to track down, collect, and dispose of the human survivors.
[edit]In film

[edit]The Terminator
Main article: The Terminator
In the first movie, Skynet is described as being a revolutionary artificial intelligence system built by Cyberdyne Systems for SAC-NORAD. According to Kyle Reese, Skynet "saw all humans as a threat; not just the ones on the other side," and "decided our fate in a microsecond: extermination." Skynet began a nuclear war which destroyed most of the human population, and initiated a program of genocide against the survivors.
Under John Connor, the human resistance turned the tide on the machines and eventually destroyed Skynet's defense grid. In a last ditch effort, Skynet sent a cyborg, called a "Terminator", back in time to 1984 to kill Connor's mother Sarah before she would give birth to John. Connor sent back his own operative, a young man named Kyle Reese, to save Sarah. The Terminator did not succeed in killing Sarah; Reese impregnated Sarah, becoming John's father; and the Terminator was destroyed in a hydraulic press.
[edit]Terminator 2: Judgment Day
Main article: Terminator 2: Judgment Day
In Terminator 2, it is revealed that, while the first Terminator had been crushed by Sarah Connor in a hydraulic press in Cyberdyne's factory, the CPU (and arm) had been recovered largely intact, but non-functional. These parts were claimed by Cyberdyne and became the basis for their later work on Skynet - a temporal paradox in the plot.
In the second film, Skynet was a direct descendant of a revolutionary microprocessor invented by Miles Bennett Dyson, a programmer for Cyberdyne.
It is revealed that Dyson's CPU design is based on the reverse engineering of the damaged CPU and arm from the Terminator depicted in the first film. Cyberdyne Systems, as depicted in the first film, was a small manufacturing company of an undefined nature, but by 1995 had grown into a major defense contractor based on the recovered Terminator technology from 1984 and Dyson's research. The company began installing these technologies in military hardware, becoming the leading weapons manufacturer. The military retrofitted all of its missile defense systems and stealth bombers with Cyberdyne technology, effectively removing human decisions from strategic defense. Skynet would later become self aware and launched its attack as an act of self defense when military commanders attempted to shut it off.
In Terminator 2, the future was altered when Sarah and a young John, together with a second Terminator from the future (this one reprogrammed and sent by the future John Connor), raided Cyberdyne Systems and succeeded in destroying the CPU and arm of the first movie's Terminator, along with the majority of research that led to Skynet's development. This also resulted in the death of Dyson. Skynet had also sent a Terminator back in time, the more advanced T-1000, to stop the reprogrammed Terminator and the Connors from altering the timeline that was also destroyed. It was believed that they had eliminated enough of Skynet's origins to ensure it could not be recreated.
[edit]T2 3-D
Main article: T2 3-D: Battle Across Time
In the Universal Studios theme park attraction T2 3-D, based on Terminator 2, a T-800 machine and a young John Connor journey into the post-apocalyptic future and attempt to destroy Skynet's "system core". This core is housed inside an enormous, metallic-silver pyramidal structure, and guarded by the "T-1000000", a colossal liquid metal shape shifter more reminiscent of a spider than a human being. But the T-1000000 fails, and the T-800 destroys Skynet once John has escaped through a time machine.
[edit]Terminator 3: Rise of the Machines
Main article: Terminator 3: Rise of the Machines
The events of Judgment Day were ultimately not prevented, merely postponed. Following the destruction of its major assets, Cyberdyne was ruined financially but some of its research and plans survived. The United States Air Force purchased the company and started in-house development of the projects in its Cyber Research Systems Division (CRS). After years of work, CRS had nearly completed Skynet, a software system designed to create new military vehicles and make real-time strategic decisions as well as protect their computer systems from viral attacks. Due to the massive computing needs and to protect it from direct attack, Skynet utilized a large network of computers that would be nearly impossible to deactivate completely. Unknown to CRS, Skynet began to spread beyond its original computing base through the Internet and various other digital media. The film also suggests that Lieutenant General Robert Brewster has always been destined as the true creator of Skynet by using Miles Bennett Dyson's works from Cyberdyne Systems, even in the original timeline without the interference of the T-800 and T-1000 in T2.
Prior to Judgment Day, Skynet had penetrated nearly every networked machine in the world, causing malfunctions in everything from barcode scanners to nuclear launch systems. This was originally believed to be the effects of a new virus, and increasing pressure was placed on the CRS to purge the corrupted systems. The CRS attempted to eliminate it from the U.S. defense mainframes by tasking Skynet with removing the infection, in essence ordering the program to destroy itself. Whether it attained sentience at that moment or had previously gained sentience is unknown, but in direct response to its orders, Skynet retaliated in order to ensure its survival. However it is also possible that Skynet had deliberately spread itself, through unknown means, using the virus as a way to gain complete control - if this is true it would indicate this incarnation is more hostile as it launched an unprovoked attack rather than acting in self defense. Skynet took control of the various machines and robots in the CRS facility and used them to kill the personnel and secure the building, eliminating the only people who might be aware of its weaknesses. John Connor attempted to attack Skynet's computer core, hoping to stop it before it proceeded to its next attack, only to find he could not. Skynet was pure software and on too many systems to be attacked. Shortly afterward, Skynet began a nuclear bombardment of the human race with the launch systems it had infected. Judgment Day thus occurred despite John Connor's efforts, suggesting the impact of the temporal tampering was largely inconsequential.
Skynet gained access to several autonomous military drones (such as the "T-1" in Terminator 3), using them to round up survivors, who were forced to build automated factories and robots that were better at constructing than the military robots. Skynet then killed these human slaves, and using the infrastructure that had been built, rapidly designed newer and better machines until 2029, when it controlled an extremely advanced empire all over the planet. It then proceeded to continue its genocide of the human race in order to ensure its continuing survival.
It is worth noting that many military machines were already created in CRS (the T-1, HK hover crafts, and in the video game Terminator 3: The Redemption, even prototype T-800s) before the Air Force activated Skynet. While the only weapons Skynet had at its disposal were nuclear weapons in the United States in 1997 and the pieces of military hardware wired into its system, an early version of Skynet's army was already created before it was even brought online, as well as gaining access to every nuclear missile with a networked computer across the world after spreading to all of the world's computers.
[edit]Terminator Salvation
Main article: Terminator Salvation
In the post-apocalyptic year of 2018, Skynet controls a global empire from its heavily-guarded fortress-factories and research installations. Outside of its facilities mechanized units wage a constant war with the Resistance. Airborne units such as Aerostats (smaller versions of the Hunter Killer-aerials), HK-Aerials and Transports survey the skies; HK-Tanks, Mototerminators (high-speed pursuit units using a motorcycle chassis), and various Terminator models patrol cities and roads; and Hydrobots (serpentine aquatic units that move in swarms) patrol the waters. Harvesters (massive bipedal units designed to capture humans and eliminate any attempting to escape) collect survivors and deliver them to large transport craft for delivery to concentration camps for quick and orderly disposal, as mentioned in the first movie. Terminator class units such as T-1, T-600, and T-700 have been developed and act as hunters and enforcers in disposal camps. Mass production has also begun on the T-800 series in at least one Skynet facility.
In its continued battle with the Resistance, Skynet activated Marcus Wright, a forerunner to the humanoid terminators. A former death-row inmate, Wright donated his body to Project: Angel, a Cyberdyne project run by the brilliant, but terminally ill Dr. Serena Kogan. After his death by lethal injection he was transformed into a human cyborg, possessing a human heart and brain with a metallic endoskeleton and skin similar to the T-800. Like the rest of Cyberdyne's research he was transferred to the USAF when they purchased the company, though he apparently remained inactive. He was later taken by Skynet and the plan to use him as an infiltration unit was developed. A Skynet chip was installed at the base of his skull and he was programmed to locate Kyle Reese and John Connor and bring them to a Skynet facility. The programming acted on a subconscious level, allowing him to work towards his goal in a human manner.
Skynet also created a signal supposedly capable of deactivating its machines and leaked its existence to the Resistance. The Resistance leader General Ashdown attempted to use the signal to shut down the defenses of the California Skynet base in prelude to an attack. However, the signal instead allowed a HK to track down their submarine headquarters and destroy it, killing Resistance Command. It is believed that Ashdown's death led Connor to be able to take command of the Resistance from him. Marcus discovered what he had become, and was programmed for. Consequently, he furiously rebelled against Skynet, tearing out its controlling hardware from the base of his skull. Having escaped the influence of his creator, he, along with Connor and Reese, rescued the remaining human captives and destroyed Skynet's San Francisco base. While a significant victory, the majority of Skynet's global network remained intact.
Marcus Wright also encounters a being on a monitor that manifests as various faces from his past, primarily that of Dr. Serena Kogan (Helena Bonham Carter). Skynet apparently has obtained information about future events based on its actions. Kyle Reese has been targeted as a priority kill, higher level than even John Connor and the Resistance leaders.