In the [Express docs](http://expressjs.com/guide/using-middleware.html), it says:

> 
> Application level middleware are bound to an instance of express, using app.use() and app.VERB().
> 
> 
> Router level middleware work just like application level middleware except they are bound to an instance of `express.Router()`. The middleware system created at the application level in the example above, can be replicated at the router level using the following code.
> 
> 
> 

In the app provided by the Express generator, I see in the main `app.js`, there is:

```
var routes = require('./routes/index');
app.use('/', routes);

```

And in `./routes/index.js`, I see this:

```
var express = require('express');
var router = express.Router();

/* GET home page. */
router.get('/', function(req, res, next) {
  res.render('index', { title: 'Express' });
});

module.exports = router;

```

What is the purpose of `app.use` passing it to `router.get` instead of simply using `app.get`? And generally, what's the difference between `app.VERB` and `router.VERB` in terms of routing?