Before MVC, a URL represented a physical .ASPX file, but MVC added an abstraction layer to map URLs with controllers and actions. The goal was to call methods calling resources in a REST way, rather than calling pages.
In an MVC framework, regardless of the technology used, a routing system maps an incoming URL with a URL route pattern corresponding to an action's controller. A routing system doesn't work with physical files.
All the URL patterns are stored in an object called routecollection.
If there's no match, a HTTP 404 error is returned.
The routing system was linked with IIS.
HTTP.sys, the listener process in IIS, redirects to the UrlRouting module, which redirects to the ASP.NET and the ASP.NET MVC pipeline.