Risks & Ethics
Hallucination
Also known as: hallucinations
In one line
When an AI confidently makes something up.
What does Hallucination mean?
A hallucination is a plausible-sounding but false output. LLMs predict likely text, not verified facts, so they can invent quotes, citations, statistics or people. Grounding with RAG and asking for sources reduces (but doesn't eliminate) hallucinations.
A real-world example
ChatGPT citing a legal case that doesn't exist.
Related terms
Large Language Model (LLM)
A neural network trained on huge text collections to predict the next word — the engine behind ChatGPT, Claude and Gemini.
Retrieval-Augmented Generation (RAG)
A technique where the AI looks things up in your documents before answering.
Grounding
Connecting an AI's answers to verified sources so it can't just make things up.