• The Aero visual theme was first introduced with Windows Vista. A visual theme is a standard look-and-feel that is applied to what you see on the screen, what you hear, and how you navigate between windows.
• The goal of Aero is to offer a pleasing user experience that is simple, easy to learn, and fun.
• The use of 3D effects, animation, and transparent visual features, enhances this visually appealing look for Windows 7 and Windows applications.
• Hardware and software requirements
• Video card with at least 128 MB of RAM (256 MB recommended)
• Graphics card driver must support:
• A minimum of DirectX9.0
• The new Windows Display Driver Model (WDDM)

If a computer does not meet these requirements, the user interface is automatically down- graded to a simpler version. If the user upgrades their graphics hardware, the new enhanced visual theme becomes available.

Figure 1-1 Transparent Windows in Aero Glass
Courtesy Course Technology/Cengage Learning

Read more about Windows Display Driver Model (WDDM) at: http://msdn2.microsoft.com/en-us/library/aa480220.aspx