The Force Quit command has been in the Mac OS for years and years. There have been different ways to access it, but it has always been there. Why would you use Force Quit?
Unfortunately, Macs have always had problems with applications freezing up, not responding. Sometimes it is the fault of the Mac OS and sometimes it is the fault of the app in question. Either way you have to quit the app and restart it. Sometimes you have to quit the app to continue using your Mac. If this happens to you here is how you Force Quit an app.
There are several ways to do this in the macOS. The first method is the most commonly used. Hold down the Command Key ⌘, Option Key ⌥ and Press the Esc key (upper left corner of the keyboard). You will get this window:
Select the app that is giving you a bad time and then click Force Quit. Once you close that window the app will quit. Usually, if an app is stuck it will have “not responding” right next to it.
The second way to Force Quit an app is to right-click on it in the Dock. Most computer mice have a right-click button. If you are using a Magic Trackpad or a Trackpad on a laptop just tap with two-fingers. A menu will pop up with some choices, one of which is “Quit”. If you hold down the Option Key ⌥ the “Quit” turns into “Force Quit”.
Select that and the app in question should quit.
You can also find the Force Quit command in the Apple Menu if nothing else seems to work for you.
I would be remiss if I did not mention the SBBOD (Spinning Beach Ball Of Death). When an app is frozen there is usually a SBBOD associated with it.
Just want to point out one more thing. Unresponsive apps occur on all operating systems, not just the Mac. But the Mac has an elegant way of dealing with it.