With all previous generation iOS devices you simply hold down the Sleep/Wake and Home buttons to force reboot. Some people call this a hard reset. After a bit of research, I discovered that the combination of buttons needed to force reset has been changed to the Sleep/Wake and Volume Down buttons.
Why is this important? This method of power down and restarting your device is used when an app or service freezes your device, locking you out of being able to do anything with the touch screen; in some cases the home button as well. Some say it's also recommended once in a while when it's been a long time since you have powered down or soft reset your iPhone 7 and/or 7 Plus.