How do I navigate using the corners in Windows 8?

Navigating the corners of your Start Screen enables you to access the Charms Bar, App switching bar, and Start overlay.

Top-left corner: Switches to your previous apps
Bottom-left corner: Switches to Start or Desktop screen. You can use the keyboard shortcut <windows> key to toggle between Start and Desktop Screen.
Top-right corner: Displays the charms from the Charms bar
Bottom-right corner: Displays the charms from Charms bar

• Moving your mouse from the top or bottom left to the middle of the screen display the App Switching Bar.
• Moving your mouse from the top or bottom right to the middle of the screen displays the Charms Bar. You can use the keyboard shortcut <windows> key + C to access the Charm bar.