CDN stands for content delivery network, and the point is distance: keep common files close to the people asking for them. Without one, every image, font, and script comes from the site’s main server. With one, copies get served from the location nearest each visitor, which cuts latency. A CDN runs on caching, so CDN problems usually look like cache problems: you updated a file and someone still sees the old one. The cloud is the broader idea of renting someone else’s infrastructure; a CDN is specifically about delivering content from many locations instead of one origin.
Picture a company that ships the same brochure to clients nationwide. If every copy ships from one office in Dallas, far-away people wait longer. Keep stacks in regional offices and the nearest one sends it faster. A CDN is that regional-office system for web files.
Why you care
Slow pages cost attention. A client clicking a glossary entry or a portal shouldn’t feel the site dragging. The question is simple: are we making every visitor walk back to one office, or serving common files from the nearest good location?