A whistleblower is someone who reports wrongdoing, illegal activity, or dangerous practices happening inside an organization they work for or know about. The word comes from the idea of a police officer blowing a whistle to alert others to a crime.

Whistleblowers often work for companies, government agencies, or other organizations where they discover something seriously wrong: a factory secretly dumping toxic waste into a river, a company lying about safety test results, or officials stealing public money. Instead of staying quiet, they report this information to authorities, journalists, or the public.

Whistleblowing takes courage because it can be risky. A whistleblower might lose their job, face legal battles, or be criticized by people who benefit from keeping the wrongdoing secret. Many countries have whistleblower protection laws to shield these people from retaliation, recognizing that society benefits when someone speaks up about serious problems that would otherwise stay hidden.

Throughout history, whistleblowers have exposed dangerous products, corrupt practices, and environmental hazards that harmed people. While the word typically describes adults in workplace situations, the principle applies anywhere: speaking up about something wrong takes courage, especially when staying silent would be easier or safer.