<P> When Finch discovered that the Machine was tracking all premeditated crimes (episode 2, "Ghosts") rather than just terrorist activities, he initially programmed it to delete the "irrelevant" cases every night at midnight, explaining to Ingram that the Machine is not built "to save somebody, we built it to save everybody ." Unknown to Finch, Ingram created a backdoor function called "Contingency", on the eve of the government handover, to allow access to the non-relevant data (shown accessed in the season 2 episode "Zero Day"). Finch is appalled that Ingram has this data sent directly to him and shuts down the routine, but reactivates it after Ingram's death . To minimize detectability, The Machine feeds him numbers in coded messages through public telephones . </P> <P> Within the ISA, the program responsible for The Machine was known as Northern Lights before--after being leaked to the public, Northern Lights was shut down . The private technology firm Decima Technologies steals a hard drive containing code from a separate artificial intelligence, Samaritan, which was commissioned by the ISA as a contingency in case Northern Lights / The Machine became unavailable . In season three, Samaritan is built and completed by Decima, and replaces Northern Lights in supplying information to the government . Samaritan takes a much more active role in covertly shaping society towards the goals set for it, including use of violence and recruitment and deployment of people in furtherance of its aims, and The Machine and its human associates go underground, spending season four under cover . </P> <P> Much of the series is from the point of view of the Machine: scene transitions are framed as video feeds of surveillance camera footage and satellite imagery, and flashbacks as the Machine reviewing past recordings in real time . In the Machine - generated perspective, individuals are marked by dashed boxes with different colors indicating the person's status in relation to The Machine and whether they pose a threat . Season four features Samaritan's point of view, using a different user interface, with some episodes jumping back and forth between the two AIs' viewpoints . Over the course of the series, the internal "thought processes" of The Machine are shown, including the prediction models and probability trees it uses . </P> <P> The Machine in its current iteration started running on January 1, 2002, following 42 failed attempts . During the season four episode "Prophets", a previous generation of The Machine's source code was shown on screen, which was that of the Stuxnet worm . It generated the first perpetrator and victim data on February 8, 2005, following three years of training by Finch . </P>

When does the new person of interest start