Aero

Aero (short for Authentic, Energetic, Reflective, and Open) is a design language introduced in Windows Vista and was used in Windows 7. It is the successor to Luna, the design language used in Windows XP. In 2011, during the development of Windows 8 and Windows Server 2012, Aero was succeeded by "Metro" design language.

Note: Aero is not available for the Home Basic and Starter editions of Windows Vista and Windows 7.

Features
The following features of Aero were incorporated in Windows Vista:
 * Aero Glass theme: Aero changes the look and feel of GUI elements, such as buttons, checkboxes, menus, and default Windows icons.
 * Windows Flip improvements: Windows Flip (Alt+Tab) in Windows Vista now shows a live preview of each open window instead of the application icons.
 * Windows Flip 3D: Windows Flip 3D (Windows key+Tab) renders live images of open windows, allowing a user to switch between them while displaying thumbnails in a 3D view.
 * Taskbar live thumbnails: hovering over the taskbar button of a window displays a preview of that window in the taskbar.

Windows Vista and Windows 7

 * Windows Basic (Not having any sort of transparency)