In the 2010 film Tron: Legacy, ISOs are “isomorphic algorithms,” a species of programs that arose naturally inside the digital world called the Grid rather than being written by a user. Kevin Flynn saw them as a discovery with the potential to resolve various scientific mysteries, but his program Clu regarded them as an abnormality, betrayed Flynn, and destroyed them. Quorra, played by Olivia Wilde, is revealed to be the last surviving ISO. The filmmakers developed the concept partly after meeting with scientists from Caltech and NASA’s Jet Propulsion Laboratory.
Source: Wikipedia: Tron: Legacy