Tech in Diagrams

What is a CDN?

A content delivery network serves copies of your content from locations close to the user.

Beginner 4 min Architecture
A copy close to the visitor
  • Hit path
  • Miss path
  • Cache fill
Without a CDN: every request makes the full trip to the originVisitorBrowser asks for/hero.jpgHIT · FASTEDGE LOCATION · NEARESTEdge cacheClose to the visitorCACHE TRAYReused until the TTL expires, then refreshedMISS · ASK ORIGINObject cached, then servedEdge · FrankfurtSame copies, other regionEdge · São PauloServes its own visitorsEdge · SingaporeFills from the same originAPPLICATIONOrigin applicationBuilds pages, handles logic andanything personal to one userAsset storeImages, video, scripts, stylesThe originals — edges only hold copiesPURGEPublish before the TTL endsTells edges to drop the old copy
A hit is answered by the nearby edge in a single short hop. A miss costs one trip to the origin, which fills the edge cache so the next visitor in that region does not pay for it.

Hover the visitor, an edge, the cache or the origin to isolate its path; click any component for a short explanation.

Next conceptWhat is CI/CD?CI/CD is an automated path from a code change to a running release, with checks at every step.