Static site generation
Also known as: SSG
Static site generation produces finished HTML files at build time, before anybody visits. The server then does nothing but hand over a file, which is the fastest and cheapest thing a server can do, and the hardest thing to break.
It suits content that changes on a human schedule rather than a per-request one: marketing sites, documentation, blogs, glossaries, legal pages. This site is generated this way, which is why its pages have no application to boot before they can be read.
The limit is obvious in the name. Anything genuinely per-user has to be fetched by the browser afterwards or rendered on the server instead, and a site with a very large number of pages has a build time that grows with it.