Ghost hacking is a fictional activity depicted in Ghost in the Shell, whereby a person -- or machine -- uses similar technologies to hacking a computer, in order to gain direct access to the conscious mind of another person. In the Ghost in the Shell universe, people have ways in which they can connect their brain directly to diverse networks. While people generally use a firewall, a good hacker or cracker can bypass it and gain direct access to the mind of the person in question. In most cases, victims do not know they have been ghost hacked unless told by an outside source.