Like any other modern operating system, macOS lets you work with several applications at the same time, and there is no need to close them at the end of each task. Specific operating system features (for example, compressed memory and App Nap) allow several applications to run quickly and take advantage of energy-saving features even when many apps are open at once.
Use the application menu
You can of course quit an app when you no longer need it, and the simplest way to do so is to select “Quit” from the menu bearing the application’s name. Remember that clicking the red button in the top left-hand corner of an application’s window closes the window, but the application itself remains open.
Use a keyboard shortcut and remember open windows
The second way to quit an application when you no longer need it is to use the CMD-Q keyboard shortcut. Holding down the Option key while selecting “Quit” reveals the “Quit and Keep Windows” option: this reopens the windows that were active in the application the next time you launch the program.
Force Quit
If an app is not responding, you can force it to quit. You can do this by selecting the Apple menu at the top left and choosing “Force Quit”, or by pressing Command-Option-Esc: then simply select the unresponsive app and choose “Force Quit”. Remember that if you force an app to quit, you may lose any unsaved changes.
Force quit the frontmost app
Similar to the previous procedure is the Shift-Command-Option-Esc combination: it immediately forces the frontmost app to quit. This is handy when, for some reason, the system appears unresponsive and you cannot bring up the window listing open applications to force one to quit.
Instantly force a specific program to quit
As well as the “Quit” option found in every application (in the menu bearing the program’s name), which you can also invoke with Cmd-Q, you can hold down the Shift key while opening the Apple menu to see the “Force Quit” option display the name of the frontmost application.
Use the CMD-TAB combination
From the app switcher that lets you move between open programs using CMD-TAB, you can stop on the program you want (while holding down CMD) and press the Q key to quit the currently selected application.
Use the Dock
Another simple way to quit an application is to find the program among those shown as open in the Dock (they are marked by a black dot) and right-click it (or use the equivalent trackpad gesture) and select “Quit”. Holding down the Alt key lets you force it to quit by selecting “Force Quit”.
Use Activity Monitor
The Activity Monitor utility displays information about the computer’s processes, apps, disks, memory and network. You can view the list of open applications (or processes), select the one you want and force it to quit by clicking the “X” icon in the toolbar (a window appears asking for confirmation).
Use Terminal
You can of course also use Terminal to force any open application to quit, which is very convenient for anyone who works with Terminal a lot. The command syntax is very simple:
killall [applicationname]
For example, to quit Mail, simply type:
killall Mail
The application will be closed immediately without asking for confirmation.
If the Finder isn’t responding
The Finder is an app like any other that is always kept open on the Mac, so there is no option to quit or close it. If the Finder stops responding, you can use “Force Quit” so that the app relaunches automatically. Simply select “Force Quit” from the Apple menu, select “Finder” in the Force Quit window and click “Relaunch”. If the system is frozen or not responding for some reason, you can use the CMD+CTRL+ALT+power button key combination to immediately force all apps to close and shut down the system (warning: no data is saved).
Enjoy!
