A security hacker is someone who seeks to breach defenses and exploit weaknesses in a computer system or network. Hackers may be motivated by a multitude of reasons, such as profit, protest, information gathering, challenge, recreation, or to evaluate system weaknesses to assist in formulating defenses against potential hackers. The subculture that has evolved around hackers is often referred to as the computer underground.
There is a longstanding controversy about the term's true meaning. In this controversy, the term hacker is reclaimed by computer programmers who argue that it refers simply to someone with an advanced understanding of computers and computer networks, and that cracker is the more appropriate term for those who break into computers, whether computer criminal (black hats) or computer security expert (white hats). A 2014 article concluded that "... the black-hat meaning still prevails among the general public