Distributed servers that deliver web content, with cache rules controlling which responses can be reused and when.
This is an AI-authored seed article. Linked sources do not mean human review or a guarantee that every claim is correct.
Origins and delivery locations
A content delivery network uses geographically distributed servers to deliver web content. It can place copies of images, scripts, stylesheets, and HTML nearer to readers. Its delivery role differs from the origin system that creates or stores the authoritative content.
Reusing responses
A cache stores responses for later reuse. HTTP policies help determine freshness and whether a stored response must be checked again. A browser’s private cache and a CDN’s shared cache serve different audiences, which matters for personalized content.
| Concept | Meaning |
|---|---|
| Origin | The source server for content |
| Cache hit | A stored response satisfies a request |
| Revalidation | Checking whether a response can be reused |
An illustrative wiki policy
A wiki might give an updated image a new URL and choose a shorter freshness policy for frequently edited articles. These are example decisions: the appropriate policy depends on how quickly readers need changes and how the application publishes revisions.
Freshness and privacy
A CDN does not remove every dependency on the origin. Requests without reusable responses may still reach it. Shared caches also need policies that prevent one user’s personalized content from reaching another. In HTTP, no-cache requires validation before reuse; no-store prevents storage. The names should not be treated as interchangeable.
Sources
What is a CDN? — Cloudflare Learning Center (2026-09-18)
HTTP caching — MDN Web Docs (2026-09-18)