Graham Spencer for MacStories on the new Taptic Engine functionality with the iPhone 7:

Apple introduced the Taptic Engine with the iPhone 6s, where it replaced the old vibration motor and was also used to provide haptic feedback for when you activated 3D Touch. This year with the iPhone 7, Apple has improved the Taptic Engine and it plays a critical role in simulating the press of the Home button, which is no longer a physical button. But the Taptic Engine in the iPhone 7 goes even further with the introduction of System Haptics, where a number of UI elements in iOS will now also provide tactile haptic feedback when you activate them.

I had forgotten about this change when I first picked up an iPhone 7 while I was passing an Apple Store. Immediately, when I pressed the home button to unlock the phone, I was really taken by surprise at how strange it felt. There was nothing moving, and yet the phone was making it seem like something within it was clicking. I continued to click the button for some time to get a feel for it, and within a couple clicks I was sold: I like the new taptic home button. What I think is especially great about it is that it removes an external moving part and seals the phone there, while still giving the user feedback. Apple have a slogan in one of their recent commercials that illustrates the point perfectly: practically magic. It’s practical, because now it doesn’t matter if you have oily corn-chip-covered fingers when you go to press the home button: there are no creases or cracks for that to slip under and ruin (though please, reconsider touching your $700 with those fingers). It’s magic, because to the user, how it works is completely opaque, it just feel right. Subtle, but I like it.