CDN

What Is CDN?

CDNs solve the speed-of-light problem: content physically far away is slow to deliver. CDNs replicate content across servers worldwide, storing content near end users. When you request content, the CDN serves from the nearest edge server, reducing latency dramatically. For users across the globe, CDN delivery is 10-100x faster than central servers.

CDNs handle static content (images, videos, JavaScript, CSS) particularly well. Dynamic content is harder (requires computation at edge) but emerging edge computing capabilities are enabling this. CDNs also protect against DDoS attacks by absorbing traffic and filtering attacks at edge.

Examples include Cloudflare, AWS CloudFront, Akamai, and Fastly. Most large websites use CDNs because the performance improvement justifies the cost. For global services, CDN is essentially mandatory for reasonable user experience in distant regions.