# Prompt Caching

> Prompt caching stores the model's processed state for a reused prompt prefix, such as a long system prompt or document, so later requests sharing that prefix are cheaper and faster.

- Identifier: PTL-0081
- Category: Prompt Optimization
- Canonical URL: https://protologue.com/t/prompt-caching/
- Also known as: context caching, prefix caching
- Introduced: 2024

## Description

Because caches match on an exact prefix, prompts are structured with stable content first and variable content last.

## Related terms

- [System Prompt](https://protologue.com/t/system-prompt/)
- [Prompt Compression](https://protologue.com/t/prompt-compression/)
- [Context Engineering](https://protologue.com/t/context-engineering/)

## Sources

- Anthropic (2024). Prompt caching. https://platform.claude.com/docs/en/build-with-claude/prompt-caching

## Cite this entry

Protologue. (2026). Prompt Caching. In Protologue: A Taxonomy of Prompting and LLM Techniques (v1.0.0, PTL-0081). https://protologue.com/t/prompt-caching/

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