Aero Peek, also called Show Desktop, is a feature introduced in Windows 7, and available in Windows 8 and Windows 10. It allows the user to view their Desktop by placing (and not clicking) their mouse over Aero Peek in the far right-side of the taskbar.
When the Desktop is shown if you click with your left mouse button all open windows will be hidden, and you'll be on the Desktop. If you click Aero Peek again, you'll be returned to all previously opened windows.
If you right-click on Aero Peek, you'll be given the option for "Show Desktop" and "Peek at Desktop." If you select "Show Desktop," it will open the Desktop.
In Windows 10 the available area for Aero Peek is reduced to almost nothing. We recommend moving the mouse to the very bottom right corner of the screen when the taskbar is visible to access Aero Peek.
If any other window is fullscreen and hiding the taskbar, Aero Peek will not work.