>Hi,
>
>I created a HelloWorld Web API solution in VS 2013. I left all the code automatically created by VS unchanged.
>On executing of this project the VS opens the browser and puts the following URL: "localhost:53757" which shows a descriptive ASP.NET page created by VS.
>Then when I add "/api/values" to this URL making it "localhost:53757/api/values" and the browser returns the array of two values (from the Controller class).
>
>I would like to understand better the WebApiConfig class which is in the APP_START folder. This class calls method Register and passes the HttpConfiguration config. I have two questions, please:
>
>1. Do I understand correctly that this class (WebApiConfig) and method are called ONLY ONE TIME when you start the Web API (project)? Why I think so: I set a debug point in this class, and the debug point is hit only once when I execute the proejct. When I add the "/api/values" to the localhost:53757 (making it localhost:53757/api/value) code in the class WebApiConfig does not fire and debut point is not hit.
>
>2. Below is the code of the WebApiConfig class. Could someone please explain it - in English - as simply as possible (if possible).
>
>

>   public static class WebApiConfig
>    {
>        public static void Register(HttpConfiguration config)
>        {
>            // Web API configuration and services
>
>            // Web API routes
>            config.MapHttpAttributeRoutes();
>
>            config.Routes.MapHttpRoute(
>                name: "DefaultApi",
>                routeTemplate: "api/{controller}/{id}",
>                defaults: new { id = RouteParameter.Optional }
>            );
>        }
>    }
>

>
>Thank you in advance.

Yup. Called only once to configure the routing for any subsequent webapi requests (that's why it's in the App_Start folder :-} )

And, since you are using config.MapHttPAttributeRoutes() you shouldn't really need any other methods if you are using the RoutePrefix attribute on your ApiController and the Route attribute on the methods.