Live tiles are among the key features of the Windows 8 Start screen. While normal (non-live) tiles measure 150 by 150 pixels, most live tiles are double-wide (310 by 150 pixels) and display dynamic information. The People tile, for instance, shows you tweets and Facebook posts from your feeds, assuming that you've set them up. As you install apps from the Microsoft Store, more dynamic tiles may appear. Live tiles first appeared in a broad fashion in Windows Phone 7 and Xbox 360 updates, but will exist across all Microsoft platforms going forward.
Navigating the Start screen is easy. If you're using a mouse with a wheel, moving the wheel scrolls left and right. If you're using a touchpad, swiping left and right (with one finger) scrolls the tile list. You can drag individual tiles to any location.
Navigating the desktop
Microsoft now partitions applications into "Windows 8" apps (formerly known as "Metro" apps) and desktop applications. The latter are those programs we all know and love from previous versions of Windows, including Microsoft Office.
You cannot boot directly into the desktop, since Microsoft wants the Start screen to be users' initial experience with Windows 8. For most people, this restriction may not be an issue, but certain vertical applications (specialized programs, such as those for point-of-sale PCs) need to boot directly into a desktop environment. Until Windows 8 versions of such programs become available, users requiring vertical applications should stick with earlier versions of Windows.
If all you need to do is launch an application, you can simply click its tile in the Start screen. If you need robust file management and navigation features, you have to access the desktop. After you boot the machine, pressing the Windows key sends you to the desktop. Unfortunately, the Windows key isn't consistent in this behavior: If you're in an app, pressing the Windows key always returns you to the Start screen. Press it again, and you're in the most recent Windows 8 app. Instead, to move to the desktop consistently, you need to be in the habit of pressing Windows-D. Another option is to move the pointer to the lower left of the screen and click there (though this method works only if you have used no other app recently).