The Terminator: The Sarah Connor Chronicles episodes "The Turk", "Queen's Gambit", and "Dungeons & Dragons" explain that after the death of Dr. Miles Bennett Dyson and the decline of the Cyberdyne Corporation, Andrew Goode, a young intern of the company and assistant to Dyson, continued their project privately under an advanced artificial intelligence chess-playing prototype, the "Turk", with Goode's partner, Dimitri Shipkov. Goode was killed by Tech-Com's Lieutenant Derek Reese, due to documentation from the future suggesting he was one of Skynet's creators.

In the episode "Samson and Delilah" it is shown that a T-1001 infiltration unit was sent from the future to head the technological corporation ZeiraCorp as its CEO, Catherine Weaver. Weaver acquired the Turk after Goode's death and used the company's resources to further develop it under the title Babylon. The episode "The Mousetrap" revealed that it is also targeting its fellow cyborgs, including a T-888 known as Cromartie...

By the season finale, it is revealed that the Turk was a red herring, while Skynet is operating as a roving worm on home computers as in Terminator 3, and the Turk has been developed into a benevolent rival AI which Catherine Weaver hoped would be able to defeat Skynet. Her exact motive against Skynet is unknown. John Henry's "brother" is apparently behind the company Kaliba, which is responsible for constructing the Hunter-Killer prototype. This AI (presumably the true precursor to Skynet) also refers to John Henry as its "brother" at one point.

In the episode "Gnothi Seauton", it was revealed that Skynet also sends its Terminators through various points in time not only to go after the Connors and other future Resistance leaders, but also to ensure the future will unfold by eliminating John Connor's own agents who were also sent to the past to interfere with its birth, ensure Skynet's creators will complete its construction, and other specific missions.

https://en.wikipedia.org/wiki/Skynet_(Terminator)