# Chain-of-density

**Source:** https://promtable.com/glossary/chain-of-density

> Chain-of-density (CoD) is a prompting technique for summarisation that asks the model to iteratively produce denser summaries — each rewrite keeps the length but adds more entities.

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Chain-of-density (CoD) is a prompting technique for summarisation that asks the model to iteratively produce denser summaries — each rewrite keeps the length but adds more entities.

Chain-of-density (Adams et al., 2023) had the model generate an initial summary, then rewrite it 4–5 times — each rewrite kept the same length but added missing entities from the source. The result: dense, information-rich summaries that consistently outperformed single-shot summarisation on entity coverage. In 2026 CoD is the default for long-document summarisation, news digests, and any case where the answer needs to be both compact and information-dense. Modern reasoning models partially handle this natively, but explicit CoD prompting still beats single-shot on dense factual material.

## When to use

- Long-document summarisation with entity coverage requirements.
- News digest generation.
- Executive summary writing.

## Common mistakes

- Stopping at iteration 2 — the gain shows up between iterations 3 and 5.
- Letting the length grow — the point is constant length with rising density.

## Related terms

- [chain-of-thought](https://promtable.com/glossary/chain-of-thought)
- [self-consistency](https://promtable.com/glossary/self-consistency)
- [system-prompt](https://promtable.com/glossary/system-prompt)

## Sources

- [Adams et al. 2023 (arXiv)](https://arxiv.org/abs/2309.04269)

*Last updated: 2026-06-01*
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