# Hallucination

> Hallucination is generated content that is fluent and plausible but unfaithful to the provided source or factually incorrect, such as fabricated citations, facts, or quotations.

- Identifier: PTL-0096
- Category: Failure Modes & Evaluation
- Canonical URL: https://protologue.com/t/hallucination/
- Also known as: confabulation, fabrication

## Description

Surveys distinguish intrinsic hallucination, which contradicts the source, from extrinsic hallucination, which cannot be verified from it. Mitigations include retrieval-augmented generation, verification methods such as chain-of-verification, allowing the model to say it does not know, and requiring quotes from supplied documents.

## Related terms

- [Retrieval-Augmented Generation](https://protologue.com/t/retrieval-augmented-generation/)
- [Chain-of-Verification](https://protologue.com/t/chain-of-verification/)
- [Sycophancy](https://protologue.com/t/sycophancy/)

## Sources

- Ji et al. (2022). Survey of Hallucination in Natural Language Generation. https://arxiv.org/abs/2202.03629

## Cite this entry

Protologue. (2026). Hallucination. In Protologue: A Taxonomy of Prompting and LLM Techniques (v1.0.0, PTL-0096). https://protologue.com/t/hallucination/

License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)