When you are working with mutliple applications open at the same time, you can quickly minimize all open application windows and show the desktop. This is useful when you need to access files or shortcuts on the desktop without closing or minimizing your active application windows manually.

To minimize all the open application windows press Win + D on your keyboard. Press the shortcut again to restore the windows to their previous state.

You can also click the small vertical strip on the far right hand side of the taskbar (just to the right of the date and time).