Windows Aero

Windows Aero (a backronym for "Authentic, Energetic, Reflective, and Open") is a design language introduced in the Windows Vista operating system. The changes made in the Aero interface affected many elements of the Windows interface, including the incorporation of a new look, along with changes in interface guidelines reflecting appearance, layout, and the phrasing and tone of instructions and other text in applications.
Windows Aero was in force during the development of Windows Vista and Windows 7. In 2012, with the development of Windows 8 and Windows Server 2012, Microsoft moved on to a design language codenamed "Metro".
History.
Windows Vista.
The Aero interface was unveiled for Windows Vista as a complete redesign of the Windows interface, replacing Windows XP's "Luna" theme. Until the release of Windows Vista Beta 1 in July 2005, little had been shown of Aero in public or leaked builds. Previous user interfaces were "Plex", which was featured in Longhorn builds 3683–4042; "Slate", which was first featured in the Lab06 compile of build 4042 and was used until the development reset, and "Jade" (builds 4074 to 4094). Microsoft started using the "Aero" theme in public builds in build 5048. The first build with full-featured Aero was build 5219. Build 5270 (released in December 2005) contained an implementation of the Aero theme which was virtually complete, according to sources at Microsoft, though a number of stylistic changes were introduced between then and the operating system's release.
Windows Aero incorporated the following features in Windows Vista.
Windows 7.
Windows Aero is revised in Windows 7, with many UI changes, such as a more touch friendly interface, and many new visual effects and features including pointing device gestures:
Discontinuation.
Windows 8 and Windows Server 2012 adopted the Metro design language, which did not inherit all elements of Aero. The Aero Glass theme was replaced by a flatter, solid colored theme. Transparency effects were removed from the interface, aside from the taskbar, which maintains transparency but no longer has a blur effect. Flip 3D was also removed; was changed to switch between Metro-style apps. 
Pre-release versions of Windows 8 used an updated version of Aero Glass with a flatter, squared look, but the Glass theme was ultimately removed for the final version.
Features.
For the first time since the release of Windows 95, Microsoft completely revised its user interface guidelines, covering aesthetics, common controls such as buttons and radio buttons, task dialogs, wizards, common dialogs, control panels, icons, fonts, user notifications, and the "tone" of text used.
Aero Glass theme.
On Windows Vista and Windows 7 computers that meet certain hardware and software requirements, the Aero Glass theme is used by default, primarily incorporating various animation and transparency effects into the desktop using hardware acceleration and the Desktop Window Manager (DWM). In the "Personalize" section added to Control Panel of Windows Vista, users can customize the "glass" effects to either be opaque or transparent, and change the color it is tinted. Enabling Aero Glass also enables other new features, including an enhanced Alt-Tab menu and taskbar thumbnails with live previews of windows, and "Flip 3D", a window switching mechanism which cascades windows with a 3D effect.
Windows 7 features refinements in Aero Glass, including larger window buttons by default (minimize, maximize, close and query), revised taskbar thumbnails, the ability to manipulate windows by dragging them to the top or sides of the screen (to the side to make it fill half the screen, and to the top to maximize), the ability to hide all windows by hovering the Show Desktop button on the taskbar, and the ability to minimize all other windows by shaking one.
Use of DWM, and by extension the Aero Glass theme, requires a video card with 128MB of graphics memory (or at least 64MB of video RAM and 1GB of system RAM for on-board graphics) supporting pixel shader 2.0, and with WDDM-compatible drivers. Aero Glass is also not available in Windows 7 Starter, only available to a limited extent on Windows Vista Home Basic, and is automatically disabled if a user is detected to be running a non-genuine copy of Windows. Windows Server 2008 and Windows Server 2008 R2 also support Aero Glass as part of the "Desktop Experience" component, which is disabled by default.
Aero Wizards.
Wizard 97 had been the prevailing standard for wizard design, visual layout, and functionality used in Windows 98 through to Windows Server 2003, as well as most Microsoft products in that time frame. Aero Wizards are the replacement for Wizard 97, incorporating visual updates to match the aesthetics of the rest of Aero, as well as changing the interaction flow.
More specifically:
Notifications.
Notifications allow an application or operating system component with an icon in the notification area to create a pop-up window with some information about an event or problem. These windows, first introduced in Windows 2000 and known colloquially as "balloons", are similar in appearance to the speech balloons that are commonly seen in comics. Balloons were often criticized in prior versions of Windows due to their intrusiveness, especially with regard to how they interacted with full-screen applications such as games (the entire application was minimized as the bubble came up). Notifications in Aero aim to be less intrusive by gradually fading in and out, and not appearing at all if a full-screen application or screensaver is being displayed—in these cases, notifications are queued until an appropriate time. Larger icons and multiple font sizes and colors are also introduced with Aero's notification windows.
Font.
The Segoe UI typeface is the default font for Aero with languages that use Latin, Greek, and Cyrillic character sets. The default font size is also increased from 8pt to 9pt to improve readability. In the Segoe UI typeface prior to Windows 8, the numeral zero ("0") is narrow, while capital letter "O" is wider (Windows 8's Segoe UI keeps this difference), and numeral one ("1") has a top hook, while capital letter "I" has equal crown and base (Windows 8's "1" has no base, and the "I" does not have a crown or base).
Icons.
Aero's base icons were designed by The Iconfactory, which had previously designed Windows XP icons.
Phrasing tone.
The Vista User Experience Guidelines also address the issue of "tone" in the writing of text used with the Aero user interface. Prior design guidelines from Microsoft had not done much to address the issue of how user interface text is phrased, and as such, the way that information and requests are presented to the user had not been consistent between parts of the operating system.
The guidelines for Vista and its applications suggest messages that present technically accurate advice concisely, objectively, and positively, and assume an intelligent user motivated to solve a particular problem. Specific advice includes the use of the second person and the active voice (e.g. "Print the photos on your camera") and avoidance of words like "please", "sorry" and "thank you".