HTTP Caching
Browser and proxy caching controlled by HTTP headers like Cache-Control, ETag, and Last-Modified. Eliminates redundant network requests for unchanged resources.
What is HTTP Caching?
Browser and proxy caching controlled by HTTP headers like Cache-Control, ETag, and Last-Modified. Eliminates redundant network requests for unchanged resources.
HTTP Caching is a intermediate-level concept that sits in the Web & Content Delivery area of system design. Engineers reach for it whenever they need to reason about real-world trade-offs in that space — not just for textbook correctness, but because real production systems at companies like Netflix, Amazon, and Google make these decisions every day.
If you want to go deeper than this definition — with diagrams, code, and a quiz to lock it in — work through the "HTTP Caching" lesson linked below. It walks through the why, the mechanism, the trade-offs, and how the giants actually use it in production.
Learn HTTP Caching in depth
Full interactive lesson with diagrams, code examples, real-world references, and a quiz.
Open the HTTP Caching lessonSee also
Related glossary terms you might want to look up next.
Caching
Storing frequently accessed data in a faster storage layer so you don't have to fetch it from the original (slower) source every time.
CDN
A network of servers distributed globally that caches content close to users. Netflix uses CDNs to stream video from servers near you, not from one central location.
TTL
Time To Live: how long a cached entry, DNS record, or packet is valid before it expires and must be refreshed or discarded.