The "Web App" is the thing that turns a request in to a response. Even if that is as simple as reading a static file and returning it unmodified as the body of

The "Web App" is the thing that turns a request in to a response. Even if that is as simple as reading a static file and returning it unmodified as the body of the response. "Web App" is just their branding. It's just a web server that can stop/start/scale automatically as opposed to being 'always-on'.