If you’ve ever used a Mac, you probably know the spinning rainbow wheel of doom, as it’s affectionately known as. It’s Apple’s cue to you that an app is slowing down your beloved Mac, and also that you should really do something about it so you can get back to work.
It means that one of your apps has crashed, and instead of closing the app automatically, Apple lets you go find it and close it manually. Most of the time, you’ll know exactly which app it is, as it will be frozen and you won’t be able to select it using your cursor.
Switching between your running apps will show you which app it is, as you’ll see a normal mouse cursor on any apps running fine, and the spinning color wheel when the frozen app is selected. Now you know which app to deal with, here’s how