Ghost in the Shell takes place in a world that has become interconnected by a vast electronic network that permeates every aspect of life.
People also tend to rely more and more on communication devices, and the first strong AIs make their appearance.
The main entity presented in the various media is the Public Security Section 9 police force (led by Major Motoko Kusanagi) which is charged to investigate cases like the Puppet Master and the Laughing Man.
The Laughing Man
The Laughing Man is a corporate terrorist hacker, who ultimately reveals to the Major that he had discovered that several corporations, in association with the Japanese government, suppressed information on an inexpensive cure to a debilitating disease in order to profit from the more expensive treatment.
He also had a fascination with J. D. Salinger's The Catcher in the Rye whose name comes from Salinger's short story, The Laughing Man.
He is an expert hacker, able to hide his physical presence by editing himself out of video feeds and cybernetic eyes, concealing his identity by superimposing an animated logo over his face, and hijacking cybernetic brains altogether, all in real-time.
Project 2501 is created for the Japanese Ministry of Foreign Affairs as a tool that could stealthily manipulate politics and intelligence, altering databases and the memories of key persons for the benefit of select individuals and organizations affiliated with the Ministry, and is equipped with unparalleled computer and hacking abilities.
The project is headed by Dr. Willis, the American head of strategic research at Neutron Corporation and a top researcher in AI, and was started approximately a year before the first known Puppet Master incident.
Project 2501 is only referred to as the Puppet Master once its handiwork has been discovered by outside sources, which includes Section 9.
Once discovered, the Puppet Master is assumed to be a human, most likely with mnemonic enhancements, who has incredible hacking skills.
However, as the criminals are revealed to have more depth than was at first apparent, the various protagonists are left with disturbing questions:
"What exactly is the definition of 'human' in a society where a mind can be copied and the body replaced with a synthetic form?"
"What exactly is the 'ghost' —the human soul— in the shell?", and
"Where is the boundary between human and machine when the differences between the two become more philosophical than physical?"
Stand Alone Complex
While originally intended to "underscore the dilemmas and concerns that people would face if they relied too heavily on the new communications infrastructure,"
Stand Alone Complex eventually came to represent a phenomenon where unrelated, yet very similar actions of individuals create a seemingly concerted effort.
This can be compared to the emergent copycat behavior that often occurs after incidents such as serial murders or terrorist attacks.
An incident catches the public's attention and certain types of people "get on the bandwagon", so to speak.
It is particularly apparent when the incident appears to be the result of well-known political or religious beliefs, but it can also occur in response to intense media attention.
For example, a mere fire, no matter the number of deaths, is just a garden variety tragedy. However, if the right kind of people begin to believe it was arson, caused by deliberate action, the threat that more arson will be committed increases dramatically.