A static site does not have to feel frozen. With a bit of JavaScript, a static page can request data from an API and update the page on the fly. That is the whole idea behind an API-only approach: HTML, CSS, and JavaScript live on a CDN, the browser calls APIs for content, and the page updates itself.

Why should teams care? It is fast, cheap, and simple. Static files load from a CDN, deploys are trivial, and scale happens without heavy servers. It also works for real sites, like a blog fed by a headless CMS API, a product grid powered by a commerce API, or a contact form that posts to a forms service.