Taptic Engine was first introduced in iPhone 6s for 3D Touch. For iPhone 7 and 7 Plus, the Taptic Engine supports the Home button, which is no longer a physical button. In addition, Apple has enhanced the Taptic Engine to introduce subtle vibrations for various system functions.
These new System Haptics are everywhere, for example when you slide open the Notification Center, you get a subtle tap as the sliding reaches the bottom of the screen. System Haptics are also available when you use Pinch to Zoom, Sliders, Switches, pull open Spotlight etc.
System Haptics can be a delight to use. You can turn it off if you find it annoying. Go to Settings > Sounds & Haptics. Scroll all the way to the bottom and turn off the “System Haptics” switch.
Please note that disabling System Haptics does not turn off all vibrations such as for 3D Touch or incoming phone calls. These other vibrations are not under System Haptics and is managed independently.