When you open multiple windows on the desktop, it can sometimes be a challenge to find and view different windows and switch between them. But you can use Aero Peek to take a quick look at other open windows without clicking away from the window you are currently working on. It allows you to preview the contents of open windows by blacking out everything else so that you can switch to the one you want.
When you highlight the thumbnail preview of an app window that you might want open, it makes every other open window transparent, so you get a clear view of the window you're looking at. Or, if you hover over a small button on the bottom right corner of the taskbar, all open windows will fade from view, for a quick peek at your desktop, gadgets, or Windows 7's freefloating widgets.