An HTML server usually has one or more directories that are accessible by the user. You can place there the static assets needed by your application (stylesheets, scripts, images).
In Express, you can put in place this functionality using the middleware `express.static(path)`, where the `path` parameter is the absolute path of the folder containing the assets.
If you don’t know what middleware is... don’t worry, we will discuss in detail later. Basically, middleware are functions that intercept route handlers, adding some kind of information. A middleware needs to be mounted using the method `app.use(path, middlewareFunction)`. The first `path` argument is optional. If you don’t pass it, the middleware will be executed for all requests.
Now your app should be able to serve a CSS stylesheet. Note that the `/public/style.css` file is referenced in the `/views/index.html` in the project boilerplate. Your front-page should look a little better now!