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If you have open programs when you force-quit your Mac, the programs will be forced to close as well, which can cause you to lose unsaved work. In some cases, force-quitting may even corrupt open programs or installers. To be as safe as possible, try to close any open programs before you force your Mac to shut down. Most Macs have a physical button with the "Power" {"smallUrl":"https:\/\/www.wikihow.com\/images\/5\/5d\/Windowspower.png","bigUrl":"\/images\/thumb\/5\/5d\/Windowspower.png\/30px-Windowspower.png","smallWidth":460,"smallHeight":460,"bigWidth":"30","bigHeight":"30","licensing":"<div class=\"mw-parser-output\"><p>I edited this screenshot of a Windows icon.\n<\/p><p>License: <a rel=\"nofollow\" class=\"external text\" href=\"http:\/\/en.wikipedia.org\/wiki\/Public_domain\">Public Domain<\/a><br>\n<\/p><\/div>"} icon that you can press to turn off your Mac:   MacBook without Touch Bar — The "Power" key is in the top-right side of the keyboard.  MacBook with Touch Bar — The "Power" button is the Touch ID section on the far-right side of the Touch Bar.  iMac — You'll find the "Power" button behind the lower-left side of the iMac's screen. Once you've found the "Power" button, press down on it and don't release it for five seconds. At this point, your Mac should be off. If you see a prompt asking you to confirm that you want to turn off your Mac, you didn't hold down the key for long enough. This will allow your Mac to fully power down before you attempt to turn it back on.

Summary:
Understand that force-quitting your Mac can cause problems. Find your Mac's "Power" button. Press and hold the "Power" button. Release the "Power" button after five seconds. Wait a minute before turning back on your Mac.