Hacking refers to the unauthorized entry into the operating system or files of a computer or computer network. Hacking can be a deliberate part of the quality control of a system's security. More often, however, hacking is done for other reasons, such as espionage, terrorism or a prank.

The concept of hacking has changed over the past four decades. First, hacking was mainly the domain of a small cadre of highly computer literate youth who viewed hacking as a malicious prank, a game, or an act of protest. With the advent of the modem and the great increase in the number of computer users, the number of hackers increased. Also, the utility of hacking as a means of espionage and political demonstration were recognized, leading to the emergence of a professional variety of hacker.

Hacking crimes are estimated to cost United States corporations upwards of $63 billion a year...