"All three of these standards attempt to create is a way of describing an API." #readingToday
A few years ago, we would have called them Web-based APIs with a capital W. Today, they're just APIs, RESTful though they may be. And it is within this tangle of HTTP calls that standards have begun to take hold. RAML, WADL and the now most popular Swagger seek to bring some cohesion to the many millions of APIs out there in the wild.
One common thing all three of these standards attempt to create is a way of describing an API in a somewhat automated fashion. This takes the form of automatically generated documentation, typically.