Black Hat hackers, SOMETIMES known as crackers, attempt to obtain unauthorized access to a system in order to disrupt its operations or steal critical data.

Because of its malicious aim, black hat hacking is always illegal, including stealing company data, violating the privacy, causing system damage, and blocking network connection, among other things.

Ethical hackers are also referred to as White hat hackers. As part of penetration testing and vulnerability ASSESSMENTS, they never intend to harm a system; rather, they strive to uncover holes in a computer or network system.
Ethical hacking is not a crime and is ONE of the most difficult professions in the IT business. Many businesses hire ethical hackers to do penetration tests and vulnerability assessments.

Grey hat hackers combine elements of both black and white hat hacking. They act without MALICE, but for the sake of AMUSEMENT, they exploit a security flaw in a computer system or network without the permission or knowledge of the owner.
Their goal is to draw the owners' attention to the flaw in the hope of receiving gratitude or a small reward.