Windows 8 is the current release of the Windowsoperating 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 1 August 2012, and was released for general availability on 26 October 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 like Android and iOS, taking advantage of new or emerging technologies like 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 capabilities, a new installation process optimized for digital distribution, and support for secure boot (a UEFI feature which allows operating systems to be digitally signed to prevent malware from altering the boot process), the ability to synchronize certain apps and settings between multiple devices, 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, and the new Windows Store to obtain and/or purchase applications to run on the operating system.Windows 8 was released to mixed reception—although reception towards its performance improvements, security enhancements, and its improved support for touchscreen devices was positive, the new user interface of the operating system has been widely criticized for being confusing and having a steep learning curve (especially when used with a keyboard and mouse instead of a touchscreen). Despite these shortcomings, 40 million Windows 8 licenses were sold during its first month of availability, mostly to original equipment manufacturers (OEMs).

New and changed features

New features and functionality in Windows 8 include a faster startup through UEFI integration and the new "Hybrid Boot" mode (which hibernates the Windows kernel on shutdown to speed up the subsequent boot), a new lock screen with a clock and notifications, and the ability for enterprise users to create live USB versions of Windows (known as Windows To Go). Windows 8 also adds native support for USB 3.0 devices, which allow for faster data transfers and improved power management with compatible devices, along with support for near field communication to facilitate sharing and communication between devices.

Windows Explorer, which has been renamed File Explorer, now includes a ribbon in place of the command bar. File operation dialog boxes have been updated to provide more detailed statistics, the ability to pause file transfers, and improvements in the ability to manage conflicts when copying files. A new "File History" function allows incremental revisions of files to be backed up to and restored from a secondary storage device, while Storage Spaces allows users to combine different sized hard disks into virtual drives and specify mirroring, parity, or no redundancy on a folder-by-folder basis.

Task Manager has also been redesigned, including a new processes tab with the option to display fewer or more details of running applications and background processes, a heat map using different colors indicating the level of resource usage, network and disk counters, grouping by process type (e.g. applications, background processes and Windows processes), friendly names for processes and a new option which allows users to search the web to find information about obscure processes. Additionally, the Blue Screen of Death has been updated with a simpler and modern design with less technical information displayed.

Safety and security

Additional security features in Windows 8 include two new authentication methods tailored towards touchscreens (PINs and picture passwords), the addition of antivirus capabilities to Windows Defender (bringing it in parity with Microsoft's Security Essentials software)SmartScreen filtering integrated into the desktop, and support for the "Secure Boot" functionality on UEFI systems to protect against malware infecting the boot process.Parental controls are offered through the integrated Family Safety software, which allows parents to monitor and control their children's activities on a device with activity reports and safety controls. Windows 8 also provides integrated system recovery through the new "Refresh" and "Reset" functions. Windows 8's first security patches would be released on 13 November 2012; it would contain three critical (most severe as per Microsoft) fixes.

Online services and functionality

Windows 8 provides heavier integration with online services from Microsoft and others. A user can now log in to Windows with a Microsoft account, formally known as a Windows Live ID, which can be used to access services and synchronize applications and settings between devices. Windows 8 also ships with a client app for Microsoft's SkyDrivecloud storage service, which also allows apps to save files directly to SkyDrive. A SkyDrive client for the desktop and File Explorer is not included in Windows 8, and must be downloaded separately. Bundled multimedia apps are provided under the Xbox brand, including Xbox Music, Xbox Video, and the Xbox SmartGlass companion for use with an Xbox 360 console. Games can integrate into an Xbox Live hub app, which also allows users to view their profile and gamerscore. Other bundled apps provide the ability to link to services such as Flickr and Facebook.

Internet Explorer 10 is included as both a desktop program and a touch-optimized app, and includes increased support for HTML5, CSS3, and hardware acceleration. The Internet Explorer app does not support plugins or ActiveX components, but includes a version of Adobe Flash Player that is optimized for touch and low power usage, but works only on sites included on a whitelist. The desktop version does not contain these limitations.

Windows 8 also incorporates improved support for mobile broadband; the operating system can now detect the insertion of a SIM card and automatically configure connection settings (including APNs and carrier branding), track and reduce bandwidth use on metered networks. Windows 8 also adds an integrated airplane mode setting to globally disable all wireless connectivity as well. Carriers can also offer account management systems through Windows Store apps, which can be automatically installed as a part of the connection process and offer usage statistics on their respective tile.

Windows Store and Apps

Windows 8 introduces a new style of application, Windows Store apps; according to Microsoft developer Jensen Harris, these apps are to be optimized for touchscreen environments and have smaller scope in relation to desktop applications. Apps can run either in a full-screen mode, or be docked directly to the side of a screen. They can provide notifications and a "live tile" on the Start screen for dynamic content. Apps can use "contracts"; a collection of hooks to provide common functionality that can integrate with other apps, such as search and sharing. Apps can also provide integration with other services; for example, the People app can connect to a variety of different social networks and services (such as Facebook), while the Photos app can aggregate photos from services such as Facebook and Flickr.

Windows Store apps run within a new set of APIs known as the Windows Runtime, which supports programming languages such as C, C++, VB.NET, C#, along with HTML5 and JavaScript. Depending on the language used, apps written for Windows Runtime can be cross-compatible with both Intel and ARM versions of Windows. To ensure stability and security, apps run within a sandboxed environment, and require permissions to access certain functionality, such as accessing the Internet or a camera.

Retail versions of Windows 8 will only be able to install these apps through the Windows Store—a namesake distribution platform which offers both apps and certified desktop applications.Sideloading, or the facility for loading Windows Store apps from outside Windows Store, is provisioned in Windows 8 Enterprise, Windows 8 Pro and Windows RT, albeit in a very limited fashion: Out-of-box sideloading support is only available for Windows 8 Enterprise computers that have joined a Windows domain. Sideloading on Windows RT and Windows 8 Pro computers as well as Windows 8 Enterprise computers without a domain affiliation requires purchase of additional licenses through Microsoft volume licensing outlet.

Windows Store apps were originally known as "Metro-style apps" during the development of Windows 8, referring to the Metro design language. The term was reportedly phased out in August 2012; a Microsoft spokesperson denied rumors that the change was related to a potential trademark issue, and stated that "Metro" was only a codename that would be phased out prior to Windows 8's release. Following these reports, the terms "Modern UI-style apps", "Windows 8-style apps" and "Windows Store apps" began to be used by various Microsoft documents and material to refer to the new apps. In an interview on September 12, 2012, Soma Somasegar (vice president of Microsoft's development software division) officially confirmed that "Windows Store apps" would be the official term for the apps.

Web browsers

Special exceptions are given to web browsers classified as being "New experience enabled" (formerly "Metro-style enabled"), which can provide a special version to run within the "Metro" shell. Unlike other apps, they can be coded using Win32 code instead of Windows Runtime (allowing the reuse of code from their desktop versions), permanently run in the background, use multiple background processes, and are distributed with desktop web browsers rather than through the Windows Store. Despite these looser restrictions, they can still take advantage of features typically reserved for Windows Store apps, such as the use of contracts to link to other apps. However, only the user's default web browser can be used in this setting.

The developers of both Chrome and Firefox both committed to developing versions of their browsers to run in the app environment; while Chrome's app simply backports the existing desktop interface, Firefox's (which is currently available in development versions) uses a touch-optimized interface inspired by the mobile version of Firefox.

Interface and desktop

Windows 8 introduces significant changes to the operating system's user interface, many of which are centered towards improving its experience on tablet computers and other touchscreen devices. The new user interface is based on Microsoft's Metro design language, and features a new tile-based Start screen similar to that of Windows Phone, which has replaced the previous Start menu entirely. The Start screen displays a customizable array of tiles linking to various apps and desktop programs, some of which can display constantly updated information and content through "live tiles". As a form of multi-tasking, apps can be snapped to the side of a screen.

A vertical toolbar known as the charms bar (accessed by swiping from the right edge of a touchscreen, or pointing the cursor at hotspots in the right corners of a screen) provides access to system and app-related functions, such as search, sharing, device management, settings, and a Start button. The traditional desktop environment for running desktop applications is accessed via a tile on the new Start screen. The Start button on the taskbar has been removed in favor of the Start button on the charms bar and a hotspot in the lower-left corner of the screen. Swiping from the left edge of a touchscreen or clicking in the top-left corner of the screen allows one to switch between apps and the Desktop. Pointing the cursor in the top-left corner of the screen and moving down reveals a thumbnail list of active apps. Aside from the removal of the Start button, the desktop on Windows 8 is similar to that of Windows 7, except that the Aero Glass theme has been replaced by a flatter, solid-colored design inspired by the Metro interface.

Secure boot

Windows 8 supports a feature of the UEFI specification known as "Secure boot", which uses a public-key infrastructure to verify the integrity of the operating system and prevent unauthorized programs such as bootkits from infecting the device.

Despite the security benefits of the feature, Microsoft faced criticism (particularly from free software supporters) for mandating that devices receiving its optional certification for Windows 8 have secure boot enabled by default using a key provided by Microsoft. Concerns were raised that secure boot could prevent or hinder the use of alternate operating systems such as Linux. In response to the criticism, Microsoft developer Tony Mangefeste stated that "At the end of the day, the customer is in control of their PC. Microsoft’s philosophy is to provide customers with the best experience first, and allow them to make decisions themselves."

Microsoft's certification requirements eventually revealed that UEFI firmware on x86 systems must allow users to re-configure or turn off secure boot, but that this must not be possible on ARM-based systems (Windows RT). Microsoft faced further criticism for its decision to restrict Windows RT devices by using this functionality, despite it being consistent with other consumer electronics with similar protection measures. No mandate is made regarding the installation of third-party certificates that would enable running alternative software.

Removed features

Aside from the removal of the Start menu, several notable features have been removed in Windows 8. Support for playing DVDs has been removed from Windows Media Player due to the cost of licensing the necessary decoders (especially for devices which do not include optical disc drives at all) and the prevalence of streaming services such as Netflix. For the same reasons, Windows Media Center will no longer be included by default on Windows 8 as well, but the software (which also includes support for DVD playback) can be added back through the paid "Pro Pack" (for the base version of Windows 8, which also upgrades the system to Windows 8 Pro) or "Media Center Pack" (for Windows 8 Pro) add-ons. Windows 8 will still support third-party DVD playback software.

File History, the new backup feature of Windows 8 described above, replaces Backup and Restore, the former backup app, and Previous Versions, a component of Windows Explorer that saves previous versions of changed files. Backup and Restore is deprecated but will continue to work on preset schedule on computers that upgrade from Windows 7 to Windows 8.^:76 Previous Versions no longer protects local files, although it is still available to access previous versions of shared files stored on a Windows Server computer.Shadow Copy, the subsystem component based on which these worked, however, is still available for other software to use.

Hardware requirements

PCs

The minimum system requirements for Windows 8 are slightly higher than those of Windows 7. Notably, Windows 8 now requires that a system's CPU support certain hardware features, specifically the PAE, NX bit, and SSE2. Windows Store apps require a screen resolution of 1024x768 or higher to run, while a screen resolution of 1366x768 or higher is required to use the snapping functionality for apps.

To receive logo certification, Microsoft requires that an x86 system resume from standby in 2 seconds or less.

Tablets and convertibles

Microsoft released minimum hardware requirements for new tablet and convertible devices designed for Windows 8, and defined a convertible form factor as a standalone device that combines the PC, display and rechargeable power source with a mechanically attached keyboard and pointing device in a single chassis. A convertible can be transformed into a tablet where the attached input devices are hidden or removed leaving the display as the only input mechanism.

Editions and pricing

Windows 8 is available in four editions; one is simply named Windows 8 and is intended for mainstream consumers. Windows 8 Pro contains additional features aimed towards power users and professional environments. Windows 8 Enterprise contains additional features aimed towards business environments, and is only available through volume licensing.Windows Media Center is not included by default in any edition of Windows 8, but will still be available for purchase as an add-on for Windows 8 Pro, or as part of a "Pro Pack" upgrade for Windows 8 which also includes the Pro upgrade.Windows RT will only be made available as pre-loaded software on new ARM-based devices built specifically for the OS.

Users of previous versions of Windows can purchase an upgrade to Windows 8 Pro online (using a download that can be optionally burned to a DVD), or through boxed copies at retail on DVD. Microsoft is offering these upgrades at a discounted price of $39.99 USD online, or $69.99 for retail box DVD, from its launch until 31 January 2013; afterwards the upgrade price will be $199. Additionally, the "Full" and "OEM" SKUs of Windows (which can be installed on a computer with no existing operating system) have been replaced by a single "System Builder" SKU, intended to be used by original equipment manufacturers and hobbyists building their own systems.

Microsoft also began to offer an upgrade program for those purchasing new PCs pre-loaded with Windows 7 Home Basic, Home Premium, Professional, or Ultimate between 2 June 2012, and 31 January 2013—in which users will be able to digitally purchase a Windows 8 Pro upgrade for $14.99 USD. The Windows Media Center add-on will be offered for free through this offer. Several PC manufacturers have offered rebates and refunds on Windows 8 upgrades obtained through the program on select models, such as Hewlett-Packard (in the U.S. and Canada on select models), and Acer (in Europe on selected Ultrabook models).

In November 2012, a complaint was filed with the Australian Competition and Consumer Commission, alleging that Microsoft was deliberately misleading consumers by not including prominent labels on Windows 8's retail packaging indicating that it is only an upgrade version that cannot be installed without an existing version of Windows present (unlike previous versions, which did contain such markings, and were sold at retail in both upgrade and full versions).

Software compatibility

The three desktop editions of Windows 8 are sold in two sub-editions: 32-bit and 64-bit. The 32-bit sub-edition runs on CPUs compatible with x86 architecture 3rd generation (known as IA-32) or newer, and can only run 32-bit applications. The 64-bit sub-edition runs on CPUs compatible with x86 8th generation (known as x86-64, or x64) or newer, and can run 32-bit and 64-bit applications. 32-bit programs and operating system are restricted to supporting only 4 gigabytes of memory while 64-bit systems can theoretically support 2048 gigabytes of memory. 64-bit operating system require a different set of device drivers than those of 32-bit operating systems.

The 32-bit edition of Windows 8 is capable of running 16-bit applications, although 16-bit support must be enabled first. 16-bit applications are developed for CPUs compatible with x86 2nd generation, first conceived in 1978. Microsoft started moving away from this architecture since Windows 95.

Windows RT, the only edition of Windows 8 for systems with ARM processors, only supports applications included with the system (such as a special version of Office 2013), supplied through Windows Update, or Windows Store apps, to ensure that the system only runs applications that are optimized for the architecture. Windows RT does not support running IA-32 or x64 applications. Windows Store apps can either be cross-compatible between Windows 8 and Windows RT, or compiled to support a specific architecture.