What Happened To User Stories

What happened to user stories? They seem to be morphing into requirements and use cases. I read now where they have turn into an acceptance test which require really requires an immense amount of detail. For example, i can't just have a short story like "user can select shipping options" and then talk about what that means later. For a test to be generated this would have to be fully designed into a form that is much larger than any index card and would be more complete than the heaviest use case.