You are correct. Spreading false information and trying to harm someone's reputation is considered a form of defamation and can have serious legal consequences. Defamation can be in the form of either slander (spoken defamation) or libel (written defamation).
If someone spreads false information about someone else and causes harm to their reputation, the affected person can file a lawsuit for defamation. To win a defamation lawsuit, the plaintiff must prove that the statements made about them were false, caused harm to their reputation, and were made with malicious intent or reckless disregard for the truth.
It's important to be careful about the information you share online and to make sure that it is accurate and truthful. If you're unsure about the veracity of a piece of information, it's best to verify it before sharing it with others.