Windows 8 is the current release of the Windows operating system, produced by Microsoft for use on personal computers, including home and business desktops, laptops, tablets, and home theater PCs. Development of Windows 8 started before the release of its predecessor in 2009. Its existence was first announced at CES 2011, and followed by the release of three pre-release versions from September 2011 to May 2012. The operating system was released to manufacturing on August 1, 2012, and was released for general availability on October 26, 2012.
Windows 8 introduces significant changes to the operating system's platform, primarily focused towards improving its user experience on mobile devices such as tablets to rival other mobile operating systems (such as Android and iOS), taking advantage of new or emerging technologies (such as USB 3.0, UEFI firmware, near field communications, cloud computing and the low-power ARM architecture), new security features (such as malware filtering, built-in antivirus software, and support for secure boot, a controversial UEFI feature which requires operating systems to be digitally signed to prevent malware from infecting the boot process), along with other changes and performance improvements.
Windows 8 also introduces a new shell and user interface based on Microsoft's "Metro" design language, featuring a new Start screen with a grid of dynamically updating tiles to represent applications, a new app platform with an emphasis on touchscreen input, the new Windows Store to obtain and purchase applications for the system, and the ability to synchronize programs and settings between multiple devices.
Windows 8 development started before Windows 7 had shipped in 2009. In January 2011, at the Consumer Electronics Show (CES), Microsoft announced that Windows 8 would be adding support for ARM microprocessors in addition to the x86 microprocessors from Intel, AMD and VIA Technologies. On June 1, 2011, Microsoft officially unveiled Windows 8's new user interface as well as additional features at the Taipei Computex 2011 in Taipei (Taiwan) by Mike Angiulo and at the D9 conference in California (United States) by Julie Larson-Green and Microsoft's Windows President Steven Sinofsky. A month before the BUILD conference was held, Microsoft opened a new blog called "Building Windows 8" for users and developers on August 15, 2011.
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 more than 500,000 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.
On 29 February 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 Charm bar. 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 is set to expire on January 15, 2013.
At Japan's Developers Day conference, 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 is set to expire on January 15, 2013.
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 x86 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 student downloads (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 its to 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 will 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.