What is server-side rendering and why does it matter for SEO?

Definition

Server-side rendering (SSR) means a web page is fully assembled at the moment it is sent to the visitor (or crawler), instead of being composed later inside the browser.

Context

On websites that only build their content client-side (a so-called single-page application), search engines and especially AI crawlers often see just an empty page — they usually don't execute JavaScript.

With SSR the full content is present in the server's first response. That immediately improves visibility in both classic search engines and AI answer engines, and also delivers a noticeably faster first render.