What Happens When You Press Alt+F4? This Is How It Works

Do you know what does Alt+F4 do and what it is the difference between Alt+F4 and other methods of closing a program? We tell you all here.

Alt+F4 is perhaps the most famous shortcut ever on Windows; however, many people surprisingly don’t understand what happens when they press the Alt+F4 shortcut and how it differs from the other close/end mechanisms on Windows, like the End task on the task manager.

Alt+F4 closes the application in the same way as if you click on the x close button. If you press ALT + F4 when a program is frozen, Windows will wait for the program to respond; if it doesn’t, Windows will give you the option to close the non-responding program.

Alt+F4 (and the x close button) does NOT force quit a program. It sends a polite request to terminate the program (through the WM_CLOSE function). Thus it is the right way to close a program.

For example, if you use this shortcut in Word or Excel, the program will ask if you want to save your file; or if you use it on a game, the game will confirm that you want to close it to avoid accidentally losing unsaved data.

Another shortcut to close programs is CTRL+F4, but there is a fundamental difference between these two shortcuts. Do you know what the difference is?

What is the difference between ALT+F4 and CTRL+F4?

Alt+F4 closes the whole application, while CTRL+F4 closes a window on an application. For example, ALT+F4 will close your browser, while CTRL+F4 will only close a certain tab. When a program is running on a single window, both shortcuts will end the program.

The CTRL+F4 shortcut can be handy when you want to close one of the multiple instances of a program, like a Word document, but want to keep still using the program.

However, ALT+F4 and CTRL+F4 won’t work well on frozen or non-responding programs because a frozen program cannot receive the close request.

In this case, it is necessary to kill the process forcefully, and we can only do it through the End Task button on the task manager.

There is a crucial difference between these seemingly similar functions of ALT+F4 and End Task.

What is the difference between ALT+F4 and End Task?

Those are two different functions. ALT+F4 (and the x close) button calls the WM_CLOSE function, but End Task calls the TerminateProcess() function.

While ALT+F4 sends a polite request to close a frozen program and gives it time to respond, the End Task function on Task Manager kills the process immediately without sending any request or giving it any chance to clean up.

You can visualize the difference in the table below:

 ALT + F4 (x close button)End Task on Task Manager
What it doesSend a polite request to terminate the applicationKill the process immediately without notifying it
Windows functionWM_CLOSETerminateProcess()
Works on frozen programs?No. After waiting for some time, Windows will prompt you to forcefully close the program.Yes, it ends immediately.
Is it safe?Yes, it will allow you to save your date or ask for confirmation before closing the application.It requires caution, as it will kill the process without giving it time to save any data, or it might kill a system application that is necessary to run the system.

Unfortunately, there is no shortcut on Windows for the End task TerminateProcess() function; however by installing an application called Super F4, you can kill a program instantly with the shortcut CTRL+ALT+F4.

Inside the task manager, however, you not only have the End task function, but you also have the End process tree.

What is the Difference Between End Task and End Process Tree?

When you access the Details tab on the Task Manager, and you right-click on any process, you will see the two options, End task and End Process tree, like in the screenshot below:

Both options end the process, but what is the exact difference between them?

End Task kills only the process, this does not include the processes spawned by it; End Process Tree kills the process and all of its child processes, that is, its process tree. When in doubt, always choose End Process Tree to ensure a program was properly terminated.

This is what a process tree looks like:

Unfortunately, it has yet to be possible to see a process tree in the Task Manager, no matter the Windows version, even though the task manager gives the option to end a process tree.

If you want to view the process tree of a certain application, as I did above, you will need the program Process Explorer.

Process Explorer is a free, advanced version of Task Manager, which Microsoft owns, so it is 100% reliable. It not only allows you to view and end a process tree, but it also lets you discover which process is locking a certain file and check if a particular process is a virus.

Here is a video tutorial on how to use it:


Alt+F4 is used to close programs, and it should be your go-to option when closing a program, as it is safe and won’t let you lose unsaved data without confirming you want to quit the program.

If you only want to close a window but not the whole application, for example, in Microsoft Word, use the CTRL+F4 shortcut instead.

When Alt+F4 doesn’t work because the program is frozen, you should kill the process in the Task Manager, either by End Task, which will kill the selected process, or End Process Tree, which will kill the parent process and its child processes.

To understand how to deal with frozen programs, read: How to Kill a Full-Screen Frozen Application on Windows 10/11?

To learn useful Task Manager shortcuts, check out my article on Task Manager Keyboard Controls You Should Know.

Laerthe Côrtes

Laerthe Côrtes

My first desktop computer, back in the 1990s, opened a whole new world for me; since then I am a heavy PC user (who will never get used to smartphones.) I worked for five years in the PC software industry, and my favorite version of Windows is still Windows 95.

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