Web development and performance
What is CDN?
A CDN is a network of servers distributed geographically that cache and serve your content from a location near each visitor. It reduces latency, absorbs traffic spikes, and for a static site can serve the whole thing without your origin being touched.
Also called: content delivery network · edge network
What it actually improves
- Time to First Byte, by removing the distance to a single origin
- Availability, because a cached copy survives an origin outage
- Compression and protocol support — Brotli, HTTP/2 and HTTP/3 come as standard on most edges
- Resilience against traffic spikes without provisioning for the peak
When you do not need one
A local business whose visitors are all within one country, on a host in that country, with a fast origin. The gain is real but small, and it is not the first thing to fix.
The unexpected benefit for small sites
Free static hosting on a CDN platform typically includes HTTP/3, Brotli and automatic TLS — and, importantly, does not run the AI-crawler denylists that some shared hosts apply at their edge. Moving host can restore crawler access that no amount of robots.txt editing could.
Where this is covered in depth
A definition can only go so far. Core Web Vitals, and the order that actually reduces them covers this properly — 3 minutes, free, no email required.
Who wrote this
Anas Bin Masud builds e-commerce sites and does technical SEO for businesses in the UK, Canada and Pakistan. These definitions come from client work rather than from a content brief — where an entry describes a mistake, it is usually one found on a real site. More about how I work.