People who break into a computer system and inform the company that they have done so. They are either concerned employees or security professionals who are paid to find vulnerabilities.

Teenage hacker Sam Curry from Nebraska earns about $100,000 a year by working 20 hours a week. He's a 'white hat' hacker, which means companies pay him, and others like him, to hack their websites ...

A person who breaks into a computer system with the purpose of inflicting damage or stealing data. In other words, a "bad guy." Contrast with white hat hacker and blue hat hacker. THIS DEFINITION ...