What is hallucination in LLMs?

Updated May 16, 2026

Short answer

Hallucination occurs when LLMs generate factually incorrect or unsupported information.

Deep explanation

LLMs predict tokens based on probability, not truth. When context is missing or ambiguous, they may generate plausible but incorrect outputs. This is a core limitation of generative models.

Real-world example

Chatbots confidently giving wrong historical facts.

Common mistakes

Assuming fluency equals correctness.

Follow-up questions

How can hallucination be reduced?
Why do LLMs hallucinate?

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