What is a Content Delivery Network (CDN)?

A Content Delivery Network, abbreviated CDN, is a globally distributed network of servers that caches and delivers content to users from the location nearest to them. Instead of every request traveling to a single origin, the CDN serves cached responses from edge nodes, reducing latency and offloading traffic.

Definition

CDNs cache static assets such as images, CSS, JavaScript, and HTML responses, and many can also accelerate dynamic content via persistent connections and request coalescing. Modern CDNs include features such as TLS termination, DDoS protection, web application firewalls, image optimization, and serverless edge runtimes. They sit between the user and the origin as a fast, programmable proxy.

Why it matters

For commerce sites, a CDN is non-negotiable. It is the single biggest lever for page-load speed across geographies, especially for first-time visitors who have nothing cached locally. It also reduces origin load, smooths traffic spikes during peaks such as Black Friday, and improves resilience by absorbing some failure modes.

Operational considerations

CDNs must be configured carefully to avoid serving stale or personalized content from the wrong cache key. Cache-Control headers, surrogate keys, and explicit purge or revalidation strategies are central. In composable architectures, the CDN typically caches the storefront output, while API calls to commerce services either bypass the CDN or use short-lived caches. Frontend management platforms automate much of this configuration.

Related

Explore Performance and Core Web Vitals · Composable Headless Frontend.