This is the public API of Cucumber. The public API includes the classes, modules and methods you can use if you are a user of Cucumber. It also applies to you if you're developing a 3rd party tool that integrates with Cucumber.
Cucumber has more classes, modules and methods than what you can see in the public API. If you decide to dive into the source code and make use of an API that isn't part of this documentation - beware that this API might change at any time. If you want a particular internal API to be promoted to the public API - let us know.