Development history

Early development

Windows 8 development started before Windows 7 had shipped in 2009. At the Consumer Electronics Show in January 2011, Microsoft announced that the next version of Windows would add support for devices with ARM microprocessors, and showcased an early version of what would become Windows 8, NT 6.2 build 7867, running on several prototype ARM devices. Details also began to surface about a new application framework for Windows 8 codenamed "Jupiter", which would be used to make "immersive" applications using XAML (similarly to Windows Phone and Silverlight) that could be distributed via a new packaging system and a rumored app store.

On June 1, 2011, Microsoft unveiled Windows 8's new user interface as well as additional features at both Computex Taipei and the D9: All Things Digital conference in California. The "Building Windows 8" blog launched on August 15, 2011, featuring details surrounding Windows 8's features and its development process.

Public betas A screenshot of Windows 8 Developer Preview running on a multi-monitor system, showcasing some features

Microsoft unveiled new Windows 8 features and improvements on the first day of the Build Conference on September 13, 2011. Microsoft released Windows 8 Developer Preview (build 8102) the same day, which included SDKs and developer tools (such as Visual Studio Express and Expression Blend) for developing applications for Windows 8's new interface. According to Microsoft, there were about 535,000 downloads of the developer preview within the first 12 hours of its release. Originally set to expire on March 11, 2012, in February 2012 the Developer Preview's expiry date was changed to January 15, 2013.

Three milestone releases of Windows 8 leaked to the general public. Milestone 1, Build 7850, was leaked on April 12, 2011. It was the first build where the text of a window was written centered instead of aligned to the left. It was also probably the first appearance of the Metro-style font, and its wallpaper had the text shhh... let's not leak our hard work. However, its detailed build number reveals that the build was created on September 22, 2010. The leaked copy edition was Enterprise edition. The OS still reads as "Windows 7". Milestone 2, Build 7955, was leaked on April 25, 2011. The traditional Blue Screen of Death (BSoD) was replaced by a new Black screen, although this was later scrapped. This build introduced a new ribbon in Windows Explorer. Build 7959, with minor changes but the first 64-bit version, was leaked on May 1, 2011. The "Windows 7" logo was temporarily replaced with text displaying "Microsoft Confidential". On June 17, 2011, build 7989 64-bit edition was leaked. It introduced a new boot screen featuring the same fish as the default Windows 7 Beta wallpaper, which was later scrapped, and the circling dots as featured in the final (although the final version comes with smaller circling dots throbber). It also had the text Welcome below them, although this was also scrapped.

On September 13, 2011, Microsoft officially presented the first public beta build of Windows 8 (build 8102, otherwise known as the "Windows Developer Preview") at its Build Conference event; a Samsung tablet running the build was also distributed to all attendees of the conference. The build was released for download later in the day in both 64-bit and 32-bit versions, with the 64-bit version available in a version with development tools for creating apps. The Windows Store was announced during the presentation, but was not available in this build.

The new File Explorer interface with "Ribbon" in Windows 8

On February 19, 2012, Microsoft unveiled a new logo to be adopted for Windows 8. Designed by Pentagram partner Paula Scher, the Windows logo was changed to resemble a set of four window panes. Additionally, the entire logo is now rendered in a single solid color.

On February 29, 2012, Microsoft released Windows 8 Consumer Preview, the beta version of Windows 8, build 8250. For the first time since Windows 95, the Start button is no longer present on the taskbar, though the Start screen is still triggered by clicking the bottom-left corner of the screen and by clicking Start on the charms. Windows president Steven Sinofsky said more than 100,000 changes had been made since the developer version went public. The day after its release, Windows 8 Consumer Preview had been downloaded over one million times. Like the Developer Preview, the Consumer Preview expired on January 15, 2013.

Many other builds were released until the Japan's Developers Day conference, when Steven Sinofsky announced that Windows 8 Release Preview (build 8400) would be released during the first week of June. On May 28, 2012, Windows 8 Release Preview (Standard Simplified Chinese x64 edition, not China-specific version, build 8400) was leaked online on various Chinese and BitTorrent websites. On May 31, 2012, Windows 8 Release Preview was released to the public by Microsoft.

Major items in the Release Preview included the addition of Sports, Travel, and News apps, along with an integrated version of Flash Player in Internet Explorer. Like the Developer Preview and the Consumer Preview, the release preview expired on January 15, 2013.

RTM and release A launch event for Windows 8 was held at Pier 57 in New York City.

On August 1, 2012, Windows 8 (build 9200) was released to manufacturing with the build number 6.2.9200.16384 . Microsoft planned to hold a launch event on October 25, 2012 and release Windows 8 for general availability on the next day. However, only a day after its release to manufacturing, a copy of the final version of Windows 8 Enterprise N (produced for European markets) leaked to the web, and several days later there were Pro and Enterprise leaks both IA-32 and x64. On August 15, 2012, Windows 8 was made available to download for MSDN and TechNet subscribers. Windows 8 was made available to Software Assurance customers on August 16, 2012. Windows 8 was made available for students with a DreamSpark Premium subscription on August 22, 2012, earlier than advertised.

Relatively few changes were made from the Release Preview to the final version; these included updated versions of its pre-loaded apps, the renaming of Windows Explorer to File Explorer, the replacement of the Aero Glass theme from Windows Vista and 7 with a new flat and solid-colored theme, and the addition of new background options for the Start screen, lock screen, and desktop. Prior to its general availability on October 26, 2012, updates were released for some of Windows 8's bundled apps, and a "General Availability Cumulative Update" (which included fixes to improve performance, compatibility, and battery life) was released on Tuesday, October 9, 2012. Microsoft indicated that due to improvements to its testing infrastructure, general improvements of this nature are to be released more frequently through Windows Update instead of being relegated to OEMs and service packs only.

Microsoft began an advertising campaign centered around Windows 8 and its Surface tablet in October 2012, starting with its first television advertisement premiering on October 14, 2012. Microsoft's advertising budget for the operating system is US$1.5–1.8 billion, making Windows 8 the industry's biggest product launch in history.