It's kind of amazing. A whole article about something called WebAPI and not a single link to a document that would describe what WebAPI really is. This is HTML, right?
No, it's HTTP. It makes it relatively straightforward for a somewhat experienced ASP.NET MVC developer to build an API that works over HTTP, uses HTTP status codes and headers for things like content negotiation. Such an API can be consumed in an HTML app using JavaScript or in a native mobile app (e.g. an iOS app using Objective C).
Yeah, I meant the document was written in HTML, that has this ingenious feature called HYPERLINKS. Anyway, the author spelled Web API incorrectly, that confused me.
http://www.asp.net/web-api