Prompt Caching
Also: context caching
Prompt caching saves a portion of your prompt — typically a large system prompt or document — so Claude doesn't need to re-process it on every request. The first call includes the full context; subsequent calls reference the cached version. The practical effect: faster responses and lower API costs when you're repeatedly sending the same long context, which is common in production applications.
Articles
Pay for your context once, not every time
Prompt caching is Claude's way of remembering the expensive part of a conversation so you don't have to re-send — and re-pay for — the same context on every request.
Prompt caching: why it matters when you're building with Claude at scale
If your application sends the same long system prompt on every request, you're paying to re-process it every time. Prompt caching stops that.