Una buena introducción lo que se cuenta en Beginner’s Guide to Static Site Generators:
Setting that aside, the advantages of using static site generators are impressive, with speed, security, and scalability among the top ones. Whatmore web developers are already adding dynamic elements with the use of 3rd party APIs, expanding the capabilities of static sites.
A static site generator is a tool that helps you build static pages out of the input files. It takes your content (from a headless CMS, for example), applies a selected template, and generates static HTML pages out of it.
The biggest difference between the SSGs approach and what is now considered the traditional web dev approach embodied in the use of WordPress is that instead of building a page on demand each time a user visits the site, SSG does this at build time. Basically, an already built page, stored on a CDN, is served to the user when he visits the website.