The Start screen
The Start screen is the new face of Windows. It's made up of a grid of colorful tiles, one for each app. Click a tile to run its app. You'll see tiles for a slew of new, lightweight apps built into Windows 8 as well as traditional applications like Microsoft Word. Even the Windows Desktop is accessed via a tile.
Some apps grab real-time information (such as upcoming events in your calendar) and display it as notifications on their tiles.
The new Charms bar on the right gives you quick access to search, system settings and more, and you'll use the scroll bar at the bottom to reach tiles that are located off the right edge of the screen.