In MVC we build the application and run it . The main core behind the application is that it  will run from the controller name and the action name.

 public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            routes.MapRoute(
                name: "Default",
                url: "{controller}/{action}/{id}",
                defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
            );
        }

This is the route page which contains entry for the Home controller by default and the action is Index.

This means whenever the project gets run this controller action will be executed.

 public ActionResult Index()
        {
            EmpRep = new EmployeeRepository();
            List<EmployeeModel> EmpMod = new List<EmployeeModel>();
            EmpMod = EmpRep.GetDetails().ToList();
            return View(EmpMod);
        }

Apart from it if you want to run any other action from the same controller or from the different controller you can it in the URL at run time.

http://localhost:57851/Home/_Edit

We have run the partial view _Edit which is inside the Home controller.