A static site has 3 components:
- HTML files (or other content to serve via the web, like .txt files)
- referenced assets (js, images, css)
- a web server
There is no database from which data is retrieved, compared to something like wordpress where all of your posts and pages live in a database. There is no server-side scripting engine with which to process information and render content.
Static site generators exist to provide you with tools like templating, shared data, and custom tags to assist in the creation of the static HTML pages that your web server will be serving.
The benefits of a static site are:
- Security. The web server is the only moving part.
- Portability. The HTML files will render the same when served from your local machine as they will on the web.
- Speed. When almost everything is cacheable, compressed, and doesn't require any data crunching, things load very fast.