Privacy can be defined broadly as the right to be left alone, both by the State and by individuals or organisations. When viewed in the context of computers, individual privacy mostly boils down to the issue of personal information. Personal information is information that refers to an individual person, such as age, marital status, criminal history, credit history, income, sexual preferences, and so on.

The privacy of an individual's personal information comprises three distinct areas. First, there is the choice of the individual to share or not to share items of personal information; there are also the choices about when and with whom to share it. Second, there is the question of when and with whom others may share your personal information; that is, do third parties keep personal information confidential? Finally, there is the question of how well an individual's personal information is...