What are Hallucinations in Large Language Models and why do they occur?

Updated May 16, 2026

Short answer

Hallucinations occur when AI models generate fluent but factually incorrect, fabricated, or misleading outputs.

Deep explanation

Large Language Models are probabilistic next-token prediction systems. They do not possess grounded understanding or factual verification mechanisms by default.

Core reason hallucinations occur:

  • Models optimize likelihood, not truth.
  • Language fluency is rewarded during training.
  • Statistical pattern completion can produce fabricated information.

Hallucinations emerge from several factors:

  1. Training Objective Limitations:
  • Next-token prediction prioritizes plausible continuation.
  1. Missing Knowledge:
  • Models may confidently invent unknown information.

3.…

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