An artificial intelligence, abbreviated AI, is a pseudo-sentient computer program designed to behave as a standalone personality. Some AI are based off of real people, such as ROSS who was based off of Rudyard Shelton.
Anti-matter Hawkeye is a unique case, since he donwloaded his cybernetic personality into a shuttlecraft and sent his organic body to die. This makes him the only character who has been both a living individual and an AI. (Card of Ten)
Since AI are programs, they can generally only exist inside the machines they were built for. Examples include Bruce Tinner's virtual-reality machine, Drake's machine, and Hawkeye's shuttlecraft. Soundwave and ROSS have both managed to escape their original machine of origin and live on the internet, capable of being anywhere and contacting anyone who uses internet-based communication lines.