A whistleblower is someone who finds out that a person or organization is doing something wrong and reports it to the authorities.

For example, if you’re working at a coffee shop, and you see your co-worker stealing from the cash register, telling your boss about it would make you a whistleblower. There are laws that say that you can’t be fired for being a whistleblower – so even if you get someone really important (like your boss) in trouble, they can’t fire you for telling the truth.