Not so long ago, desktop environments tended to be variations on a dominant theme. Designed to help the user interact with key parts of the operating system, these interfaces featured icons, toolbars, windows, and folders, and required you to click, scroll, or drag-and-drop to get tasks done.
Then the mobile world took off. From touch-enabled Windows 7 to Ubuntu Linux's Unity to Mac OS X Lion to Windows 8's Metro, today's OSs look more and more like their mobile brethren. Most people are already accustomed to one desktop or another, but we rarely see the alternatives side by side. Take a look at some of todays' key contenders.