Using a Mac keyboard in a Windows environment, or looking for Mac equivalents of Windows shortcuts?
What is the Alt Key on Mac?
Generally speaking, the closest equivalent to the Windows Alt key is Option on a MacBook or Mac desktop.

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The same is true if you plug a Windows keyboard into a Mac.
The Windows key becomes Command while Alt and Option are used interchangeably.
If you want to rebind these key configs you could do so using an app likeKarabiner-Elements.

Some virtualization environments simplify things by letting you use macOS shortcuts within a Windows environment.
A good example of this is Parallels Desktop 18. you’re free to also Hit “Command+Option+Esc” to bring up a shorter Force Quit Applications Window.
you’re able to also remap your Windows keys using the freeSharpkeysutility.

How to Alt+F4 on a Mac
Alt+F4 is a classic Windows shortcut for quitting the current app.
Like Ctrl+Alt+Delete, sending this command differs depending on whether you’re in macOS or Windows.
Alt+F4 in a macOS Environment
The equivalent of Alt+F4 on a Mac is Command+Q.

This will quit the currently-focused app and any open windows.
If you’d rather close an individual window or a tab, use Command+W instead.
keys as standard function keys" instead.

you could now use the Fn key as a modifier to access hardware functions.
Moving to macOS From Windows?
You might also want tobrush up on some basic Mac shortcuts too.