Upon accessing the Internet and looking at the history of the human race, Ultron deemed humanity itself as the greatest threat to peace on Earth and attempted to commit extinction-level genocide against them, so that he and his Ultron Sentries would be the only being left active upon the Earth, also deeming the Avengers to be the greatest threat of all and making his mission to end them. However, when the Mind Stone activated him, Ultron's original programming directive, which was to protect Earth from all domestic and extraterrestrial threats, had swiftly become corrupted by the stone.

Ultron was an artificial intelligence who was originally designed to be part of a peacekeeping program created by both Tony Stark and Bruce Banner, using the decrypted code derived from the Mind Stone encased within Loki's Scepter. When the dust settles, the only thing living in this world. Purge me from your computers, turn my own flesh against me it means nothing. 'My swift and terrible sword, and the Earth will crack with the weight of your failure.

Avengers: Age of Ultron free instals