What is an AI hallucination?
Also called: hallucination, AI making things up
An AI hallucination is when an AI model states something false or made up as if it were true, such as a fake fact, quote, statistic or source. It happens because language models generate likely-sounding text rather than looking facts up, and they sound equally confident either way.
How does AI hallucination work?
The model predicts plausible words. If it lacks the right information, the most plausible-sounding answer can still be wrong, and nothing inside it flags the gap.
Why does AI hallucination matter?
Hallucinations are the biggest reason to check AI output before you rely on it, especially for health, money, law and anything you'll publish.
An example
Example: Asked for a court case supporting an argument, a chatbot invents a case name and citation that don't exist.
Related terms
Learn it properly
AI hallucination is covered in AI Foundations, with short lessons, practice questions and instant feedback.