Skynet is the artificial intelligence system in James Cameron’s Terminator 2: Judgment Day.
In the Terminator story, Skynet is a military computer network that becomes self-aware and initiates a nuclear exchange known as Judgment Day. It then uses machines, including Terminators, in its war against the human survivors. The system is therefore both the source of the future threat and the force behind the time-travel mission targeting John Connor.
Terminator 2 expands the mythology established by The Terminator. Sarah Connor learns that the future is not necessarily fixed, while John discovers that technology can be used for protection as well as destruction. The film’s conflict focuses on preventing Skynet from reaching the point at which it launches the nuclear war.
Skynet is sometimes confused with the T-800, but they are not the same entity. The T-800 is a physical machine sent on a mission; Skynet is the artificial intelligence directing the machine war.