The iPhone 4s arrived with Siri, Apple’s voice assistant. The iPhone 5s introduced Touch ID. The signature feature on the next iPhone is likely to be Healthbook, Apple’s first step into health and fitness tracking.

We’ve now seen “complete recreations of screenshots,” purportedly showing Healthbook, courtesy of 9to5Mac. As you can see, the app looks a lot like Apple’s Passbook app. But instead of loyalty cards, the app tracks health and fitness data points. It includes sections that can track blood work, heart rate, hydration, blood pressure, physical activity, nutrition, blood sugar, sleep, respiratory rate, oxygen saturation, and weight.

The report notes:

While other publications have reported to the contrary, the images clearly show that Apple is working on tracking hydration levels. Also contradicting other reporting, these images do not indicate that Apple is working on tracking stress or pregnancy data points. It is possible that this type of functionality could arrive in the future, but I do not believe Apple is currently developing those capabilities.

So how does the iPhone receive the information to populate Healthbook?

Mark Gurman of 9to5Mac says “I believe that the data will be sourced from at least one of four possibilities: the iPhone itself, third-party App Store apps, third-party devices, or a future Apple wearable device (iWatch).”

Apple is likely to unveil Healthbook alongside iOS 8 later this year.

For more information, see: The AppAdvice Week In Review: The Apple TV Gaming Device, iOS 8 And MoreConcept: New Mockups Imagine How iOS 8′s ‘Healthbook’ Might Look, and Could Apple’s iPhone 6 Also Include Pressure, Humidity Sensors?