Hi! Everyone, hope you all are fine.
Today in this post I will tell you how you can use Windows Key in many different ways. Windows key is the which have four squares made on it and stuck in the middle of Ctrl and Alt key (left side of your keyboard), Mostly use (if anyone use it)as the shortcut key for opening Start menu 
at the down-left corner of your screen.
Image credit: Sparks68
Below I will refer Windows key as Windows icon 
- : Start menu
- + B = Focus on Notification bar (beside where you see time)
- + D = Minimize all window and goes to the desktop (if you press it twice it will reopen all the window which get minimize)
- + E = Windows Explorer
- + F = Search window (to search files and folder in your computer)
- + G = Bring Windows Sidebar gadgets in front and makes the focus it
- + L = Lock the active user (if it is password protected) and switch user
- + R = Opens Run dialog box
- + T = Focus on items opened in Taskbar
- + U = Open Utility Manager also known as Ease of Access
- + M = Minimize all window
- + Shift + M = Restore windows that were minimized with + M
- + F1 = Windows Help window
- + Alt + Entre ↵ = Open Window Media Center
- + 1 / 2 / 3 / 4 and so on = Switch between windows
- + + / - = Open the Magnifier Utility
- + Ctrl + F = Find Computer
- + Ctrl + Alt + Entre ↵ = Open Properties of any selected files and folder
- + Tab ⇆ = Change/cycle focus on desktop and Taskbar (may not work if all application is not minimize)
- + Pause / Break = System Properties
- + Shift + ← / → arrow key = Move the active window from one monitor to the other (when more than one monitor is used)
- + Ctrl + Tab ⇆ = Focus goes to Quick launch toolbar (use Tab, left arrow and right arrow key to navigate) (may not work if all application is not minimize)
Note: – Some of the function may not work in Windows XP. If you don’t have Windows key on your keyboard then you can use Ctrl + Esc to open Start menu.