Content Delivery Network (CDN)
A CDN is a network of edge servers that cache and serve your content close to users, cutting latency and origin load by answering most requests without a round trip to your servers.
also: CDN · content delivery network · edge network
Instead of every request travelling to one origin, a CDN keeps copies at points of presence around the world and serves each user from a nearby one. That cuts the network distance (and so TTFB), absorbs traffic spikes the origin could not, and shields the origin from load and from many denial-of-service attacks, because the edge takes the hit first.
Modern CDNs do more than cache static files: they terminate TLS, compress and optimise assets, and increasingly run code (edge functions) near the user. The economics are the same lever as cache hit ratio: every request the edge answers is one your origin does not pay compute and egress for, so a high hit ratio is what turns a CDN from a latency tool into a cost-saving one.
faq
Questions & answers
- What does a CDN actually do?
- It caches your content on edge servers near users and serves requests from the closest one, so most requests never reach your origin. That lowers latency, reduces origin compute and egress cost, smooths out traffic spikes, and absorbs a lot of attack traffic at the edge.
- Does a CDN help with dynamic content?
- Yes, in two ways. It still shortens the network path and terminates TLS near the user even for uncached responses, and modern CDNs can cache dynamic responses for short TTLs or run logic at the edge. The savings are largest for cacheable content, but the latency and security benefits apply to everything routed through it.
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