Glossary · Prompting & context
Prompt Cache
Reuse of provider-side or application-side computation for an identical or eligible prompt prefix so repeated inference avoids some preprocessing work.
Why it matters
Stable instructions and large shared documents can become cheaper or faster across repeated calls when the provider's cache contract is satisfied.
In practice
Place stable policy text before request-specific content, monitor cache-hit metadata, and treat misses as normal because eligibility and lifetime vary by provider.
Common confusion
A prompt cache is a provider or application reuse contract and may use prefix caching internally. Prefix caching specifically reuses eligible exact-token KV state, while semantic caching reuses a prior result for a sufficiently similar request.
Related terms
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