What is the Windows key for? Can I get a list of hotkey combinations for my Windows 8 system?

The Windows key on your keyboard is a hotkey that allows you to access different parts of your Windows 8 system quickly. The Windows key is located on the buttom row of your keyboard.

Here is list of the most commonly used Windows 8 hotkeys:

Windows       Switch between Start sreen and current app
Windows+C     Open the charms
Windows+D     Switch between Desktop and Start screen
Windows+E     Open Windows Explorer
Windows+F     Open the Search charm to search files
Windows+H     Open the Share charm
Windows+I     Open the Settings charm
Windows+J     Switch the main app and snapped app
Windows+L     Lock the screen
Windows+K     Open the Devices charm
Windows+O     Lock the screen orientation (portrait or landscape)
Windows+Q     Open the Search charm to search apps
Windows+R     Open the Run command dialog box
Windows+T     Cycle through open apps on the taskbar
Windows+W     Open the Search charm to search settings
Windows+X     Open options for Control Panel, Command Prompt, etc.
Windows+Z     Show the commands available in the app
Windows+Up    Maximize current app window
Windows+Down  Minimize current app window
Windows+Space Switch input language and keyboard layout
Windows+Tab   Cycle through open apps (except desktop apps)
Windows+Ctrl+Tab Cycle and snap through open apps
Ctrl+Alt+Del  Access to switch user, change password, shutdown, etc.