Hacker is a user who hacks in various systems.
In the computer security context, a hacker is someone who seeks and exploits weaknesses in a computer system or computer network. Hackers may be motivated by a multitude of reasons, such as profit, protest, challenge, enjoyment, or to evaluate those weaknesses to assist in removing them. The subculture that has evolved around hackers is often referred to as the computer underground and is now a known community.While other uses of the word hacker exist that are not related to computer security, such as referring to someone with an advanced understanding of computers and computer networks, they are rarely used in mainstream context.They are subject to the longstanding hacker definition controversy about the term's true meaning. In this controversy, the term hacker is reclaimed by computer programmers who argue that someone who breaks into computers, whether computer criminal (black hats) or computer security expert (white hats), is more appropriately called a cracker instead.Some white hat hackers[who?] claim that they also deserve the title hacker, and that only black hats should be called "crackers".