>>>>>Hi,
>>>>>
>>>>>I have a source code of an Web API project created with API template in VS 2013. Someone else created this project.
>>>>>
>>>>>If I want to see the "flow" of classes/methods when a client calls an endpoint of this Web API (just as a way to learn more). Where (in which class and/or method) would I set the Debugger to stop, so that I can follow from this point? That is, what is the Startup class/method for typical Web API template project?
>>>>>
>>>>>TIA
>>>>
>>>>Dimitry has given an example of a controller using attribute routing (but the controller will be derived from the ApiController class not Controller).
>>>>
>>>>If the site uses convention based routing then there will be a RouteConfig.cs file in the App_Start folder. Inspecting this should allow you to work out which controller and method will be called for a specific url
>>>
>>>I use Controller and not ApiController and it works very well.
>>
>>Hmm. Controller is for System.Web.Mvc - the System.Web.Http.ApiController should be used with Web API - it's better suited to returning serialized data etc.
>
>Sorry Viv, I don't understand what you mean by "better suited to returning serialized data etc.". I use WebAPI with MVC, that is right and happy with it as much as one can be using .Net technologies. Actually, I am moving by API into Go for a much better experience (if better meant much faster, really works on multiple platforms etc:).

AFAIK Controller has to return an ActionResult. The ApiController can return data serialized/formatted as per the request (JSon, XML etc.).
Google 'Differences between Controller and ApiController'