Routing
As mentioned in previous chapters, routing within Yii2 is managed by the UrlManager component defined in our application configuration. The router in Yii2 is responsible for determining where Yii2 routes external URI requests to internal controllers and actions. In Chapter 5, Modules, Widgets, and Helpers, we covered the basics of how to create and manipulate URL routes with the yii\helpers\Url helper. In this section, we'll cover how Yii2 routes these requests inside our application by exploring Yii2's UrlManager in more detail.
Routing in Yii2 can be broken down into two basic steps. The first of these steps is to parse the incoming request and query parameters (which are stored in the GET parameters of our request with the r parameter by default but can be retrieved from the request URI if we have pretty URLs enabled). The second step is to create an instance of the corresponding controller action, which will ultimately handle the request.
By default, Yii2 will break the route down...
