Cyberlibel is a catchphrase for defamation that takes place through the Internet, either on messageboards, email, blogs, chatrooms, personal websites, or other published articles. Defamation, in real life, means that someone has communicated a false and damaging statement to a third party that does verifiable harm to the defamed person's reputation. Since cyberlibel occurs over cyberspace, it raises legal issues of free speech, public figures, opportunities to refute the statements, and anonymity that may warrant new laws and regulation.

Traditionally, libel occurring through newspapers, magazines, fliers, or letters, made distinctions between a public and private figure. That is, a public figure such as a politician has less of an expectation of privacy regarding his or her activities. Also, it is easier for him or her to publicize their response or defense to damaging information to correct the public's opinion. Yet an individual who is not in the public eye has a greater protection of their reputation. Since they cannot easily reach the people who have learned misinformation, they're more likely to win a libel case.

The difference with cyberlibel is that it effectively makes otherwise private figures public, by way of websites that many people access. Also, libel laws are determined by state and jurisdiction, but there are no geographical limits to information on the internet. Analysts studying cyberlibel only have a few United States cases on which to base their opinions, and those cases are contradictory. For instance, they comment on the responsibility of an original writer, such as a blogger, versus a distribution outlet, such as a host server or messageboard that might or might not have control over editing.

Cyberlibel laws are still in flux all over the world. Some systems believe that the internet is a unique medium for free speech and democratic dissemination of information, while others want the web regulated like other publishing mediums, like newspapers. Some cite how easy it is to correct the record by posting your own blog entry, article, or messageboard response that reduces the need for legal protection of your reputation. Others want internet service providers to take more responsibility and liability for the quality of information posted through their hosting. We may need to wait decades for these questions to acquire a judicial precedent in the United States.