New and changed features

Main article: Features new to Windows 8

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, and hard disk 4Kn Advanced Format support, as well as 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, including system recovery from USB drive. Windows 8's first security patches would be released on November 13, 2012; it would contain three fixes deemed "critical" by the company.

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 SkyDrive cloud 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. Initially, Adobe Flash would only work on sites included on a "Compatibility View" whitelist; however, after feedback from users and additional compatibility tests, an update in March 2013 changed this behavior to use a smaller blacklist of sites with known compatibility issues instead, allowing Flash to be used on most sites by default. 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 apps A desktop application on Windows 8, with the Wikipedia App docked to the right as a sidebar.

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 will be more specialized than current desktop applications. Apps can run either in a full-screen mode, or be snapped to the side of a screen. Apps can provide toast notifications on screen or animate their tiles on the Start screen with 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, Skype, and People service), 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 compatible with both Intel and ARM versions of Windows. Components may be compiled as Windows Runtime Components, permitting consumption by all of the Windows Runtime supported languages. 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 be able to install these apps only through the Windows Store—a namesake distribution platform which offers both apps, and listings for desktop programs certified for comparability with Windows 8. A method to sideload apps from outside the Windows Store is available to devices running Windows 8 Enterprise and joined to a domain; Windows 8 Pro and Windows RT devices that are not part of a domain can also sideload apps, but only after special product keys are obtained through volume licensing.

The term "Immersive app" had been used internally by Microsoft developers to refer to the apps prior to the first official presentation of Windows 8, after which they were referred to as "Metro-style apps" in reference to the Metro design language. The term was 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 replaced 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) confirmed that "Windows Store apps" would be the official term for the apps.

Web browsers

Exceptions to the restrictions faced by Windows Store apps are given to web browsers; the user's default browser can provide a "New experience enabled" (formerly "Metro-style enabled") version that runs within the "Metro" shell like other apps. Web browser apps are distributed alongside desktop web browsers, and also have access to functionality unavailable to other apps, such as being able to permanently run in the background, use multiple background processes, and use Windows API code instead of WinRT (allowing for code to be re-used with the desktop version, while still taking advantage of WinRT features such as contracts to integrate with charms).

The developers of both Chrome and Firefox committed to developing versions of their browsers to run in this environment; while Chrome's "Windows 8 mode" uses the existing desktop interface, Firefox's Metro version (which is currently available in development builds) uses a touch-optimized interface inspired by the Android version of Firefox.

Interface and desktop

Windows 8 introduces significant changes to the operating system's user interface, many of which are aimed at improving its experience on tablet computers and other touchscreen devices. The new user interface is based on Microsoft's Metro design language, and uses a Start screen similar to that of Windows Phone as the primary means of launching applications. 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. Alongside the traditional Control Panel, a new simplified and touch-optimized settings app known as "PC Settings" is used for basic configuration and user settings. It does not include many of the advanced options still accessible from the normal Control Panel.

A vertical toolbar known as the charms (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 Start screen. The Start button on the taskbar has been removed in favor of the Start charm and a hotspot in the lower-left corner of the screen, which displays a large tooltip displaying a thumbnail of the Start 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.

Blue Screen of Death in Windows 8 Secure boot See also: Unified Extensible Firmware Interface#Secure boot and Hardware restrictions#Windows 8

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.

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. Tom Warren, in an article on The Verge, said that other smartphones and tablets are typically sold in a locked-down state. No mandate is made regarding the installation of third-party certificates that would enable running alternative software.