Did you notice the window key in your keyboard? it located mostly between CTRL and ALT Key.Win key have many function. Firstly, of course to open the "start tab". Other function of win key listed below

WK+e - starts the Windows Explorer
WK+f - starts the Find in Files dialog
WK+Ctrl+f - starts the Find a Computer on the Network dialog
WK+M - minimizes all the windows to clear the desktop
WK+Shift+M - restores all the minimized windows
WK+r - starts the Run dialog
WK+F1 - starts Windows Help
WK+Pause - starts System Properties