Also called a "touch pen," many people find using the stylus more comfortable than tapping and swiping with their fingers, no matter whether they have big or small hands. See stylus and touchscreen.
Touch ID is Apple's original attempt at biometric authentication still used today. It was first introduced in the iPhone 5S Home Button, then later implemented in iPads and the Mac Magic Keyboard.
The app also lives on the iPhone though, where your documents will sync if you set up a free Moleskine account. On iPhone in portrait orientation the layout is rearranged a bit, with the Pen Dock at ...