Before the advent of component-based frameworks like React, Svelte, and Vue, rendering all content via your web server was commonplace. In those days, navigation through a website would result in multiple requests to the server, rendering content and sending it back to the web browser in HTML, CSS, and JS. This is called Server-Side Rendering (SSR).
Server-side rendering — static and dynamic
After React and other component-based frameworks popped into the scene, the far less prevalent Client-Side Rendering (CSR) method became developers' go-to choice. They became fond of creating Single Page Applications where more and more of the responsibilities of rendering content were pushed from the web server onto the browser.