Hallucination
When an AI model confidently states something false or generates details that do not exist — invented facts, fake citations, impossible object physics, or six-fingered hands in images. It happens because generative models predict plausible output, not verified truth. Practical defenses: verify factual claims from LLMs, use RAG to ground answers in real documents, and in images, inspect small details (text, hands, logos) where hallucination concentrates. Example: an LLM inventing a convincing-sounding but nonexistent camera model for your prompt — harmless in art, dangerous in a product spec sheet.