Cache-Control
HTTP header that defines how long and where a response can be cached (browsers, CDNs, intermediaries).
Definition
The Cache-Control response header tells caches (browsers, CDNs, and sometimes crawler infrastructure) how to store and reuse the response. Common directives: max-age=N (cache for N seconds), public / private, stale-while-revalidate, no-cache, no-store. Well-chosen values balance freshness for updated content with reduced load and latency. For content that changes occasionally (e.g. blog posts), max-age with stale-while-revalidate is often used.
Relevance to GEO
AI crawlers and retrieval systems may cache responses. Appropriate Cache-Control ensures they see updated content when it matters while avoiding unnecessary refetches. Use with ETag for conditional requests.