Windows 10 Mobile is a mobile Version of Windows 10 developed by Microsoft. It is the successor to Windows Phone 8.1 and an iteration of the Windows Phone product line. However, it is treated as an edition of Windows 10, Microsoft's operating system for computers as part of Microsoft's plans to unify their platforms into one converged operating system.
Windows 10 Mobile aims to provide greater consistency with its personal computer counterpart, including more extensive synchronization of content, a new universal application platform that allows one app to run on multiple Windows 10 device such as personal computers, mobile devices, and Xbox, as well as the capability, one supported hardware, to connect to an external display and use a "PC-like" interface with mouse and keyboard input support. Microsoft has built tools for app developers to easily port their Android and iOS applications with minimal modifications. Windows Phone 8.1 smartphones are eligible for upgrade to Windows 10 Mobile, dependent on manufacturer and carrier support.
Microsoft had already begun the process of unifying the Windows platform across device classes in 2012; Windows Phone 8 dropped the Windows CE-based architecture of its predecessor, Windows Phone 7, for a platform built upon the NT kernel that shared much of the same architecture with its PC counterpart Windows 8 including file system (NTFS), networking stack, security elements, graphics engine (DirectX), device driver framework and hardware abstraction layer. At Build 2014, Microsoft also unveiled the concept of "universal" Windows apps. With the addition of Windows Runtime support to these platforms, apps created for Windows 8.1 could now be ported to Windows Phone 8.1 and Xbox One while sharing a common codebase with their PC counterparts. User data and licenses for an app could also be shared between multiple platforms.
In July 2014, Microsoft's then-new CEO Satya Nadella explained that the company was planning to "streamline the next version of Windows from three operating systems into one single converged operating system for screens of all sizes," unifying Windows, Windows Phone, and Windows Embedded around a common architecture and a unified application ecosystem. However, Nadella stated that these internal changes would not have any effect on how the operating systems are marketed and sold.
On September 30, 2014, Microsoft unveiled Windows 10; Terry Myerson explained that Windows 10 would be Microsoft's "most comprehensive platform ever," promoting plans to provide a "unified" platform for desktop computers, laptops, tablets, smartphones, and all-in-one devices. Windows 10 on phones was publicly unveiled during the Windows 10: The Next Chapter press event on January 21, 2015; unlike previous Windows Phone versions, it would also expand the platform's focus to small, ARM-based tablets. Microsoft's previous attempt at an operating system for ARM-based tablets, Windows RT (which was based upon the PC version of Windows 8) was commercially unsuccessful.
During the 2015 Build keynote, Microsoft announced the middleware toolkit "Islandwood", later known as Windows Bridge for iOS, which provides a toolchain that can assist developers in porting Objective-C software (primarily iOS projects) to build as Universal Windows Apps. An early build of Windows Bridge for iOS was released as open source software under the MIT License on August 6, 2015. Visual Studio 2015 can also convert Xcode projects into Visual Studio projects. Microsoft also announced plans for a toolkit codenamed "Centennial", which would allow desktop Windows software using Win32 APIs to be ported to Windows 10 Mobile.
At Build, Microsoft had also announced an Android runtime environment for Windows 10 Mobile known as "Astoria", which would allow Android apps to run in an emulated environment with minimal changes, and have access to Microsoft platform APIs such as Bing Maps and Xbox Live as nearly drop-in replacements for equivalent Google Mobile Services. Google Mobile Services and certain core APIs would not be available, and apps with "deep integration into background tasks" were said to poorly support the environment.
On February 25, 2016, after already having delayed it in November 2015, Microsoft announced that "Astoria" would be shelved. Microsoft argued that an Android emulator was ultimately redundant to the native, Objective-C toolchain, because iOS was already a primary target in multi-platform mobile development. The company also encouraged use of products from Xamarin (which they had acquired the previous day) for multi-platform app development using C# programming language instead. The Windows Subsystem for Linux was developed from Project Astoria.
In accordance with Microsoft's branding strategy, this operating system will be branded primarily as an edition of Windows 10, rather than "Windows Phone 10". Microsoft had begun to phase out specific references to the Windows Phone brand in its advertising in mid-2014, but critics have still considered the operating system to be an iteration and continuation of Windows Phone due to its lineage and similar overall functionality. Microsoft referred to the OS as "Windows 10 for phones and small tablets" during its unveiling, leaked screenshots from a Technical Preview build identified the operating system as "Windows 10 Mobile" and the technical preview was officially called the "Windows 10 Technical Preview for phones". Internally, the Microsoft Edge user agent on Windows 10 Mobile still contains a reference to "Windows Phone 10".
On May 13, 2015, Microsoft officially confirmed the platform would be known as Windows 10 Mobile.
As with Windows Phone, Windows 10 Mobile supports ARM system-on-chips from Qualcomm's Snapdragon line. In March 2015, Ars Technica reported that the operating system will also introduce support for IA-32 system-on-chips from Intel and AMD, including Intel's Atom x3 and Cherry Trail Atom x5 and x7, and AMD's Carrizo. However, as of November 2016, it did not happen.
Minimum specifications for Windows 10 Mobile devices are similar to those of Windows Phone 8, with a minimum screen resolution of 800×480 (854×480 if software buttons are in use), 1 GB of RAM and 8 GB of internal storage. Owing to hardware advancements and the operating system's support for tablets, screen resolutions can now reach as high as QSXGA resolution (2560×2048) and further, as opposed to the 1080p cap of Windows Phone 8. The minimum amount of RAM required is dictated by the screen's resolution; screens with a resolution 800×480 or 960×540 and higher require 1 GB, 1920×1080 (FHD) or 1440×900 and higher require 2 GB, and 2560×1440 and higher require 3 GB.
Microsoft unveiled flagship Microsoft Lumia smartphones during a media event on October 6, 2015, including Lumia 950, Lumia 950 XL, and the low-end Lumia 550.
Microsoft announced Windows 10 Mobile during their January 21, 2015 event "The Next Chapter". The first Windows 10 Mobile build was rolled out on February 12, 2015 as part of the Windows Insider Program to a subset of mobile devices running Windows Phone 8 and 8.1. As with the desktop editions of Windows 10, this initial release was codenamed "Threshold", it was part of both the "Threshold 1" and "Threshold 2" development cycles. Windows 10 Mobile launched with the Microsoft Lumia 550, 950 and 950 XL. The rollout for Windows Phone 8.1 devices started March 17, 2016.
On February 19, 2016, Microsoft restarted the rollout of full builds for the first feature update, officially known as the "Anniversary Update" or "Version 1607", codenamed "Redstone 1". Like the start of the previous wave, the first builds were not available to all devices that were included in the Windows Insider Program.
Codename "Redstone 2" is the second major update to Windows 10 Mobile. The first preview flighted out to Insiders on August 17, 2016.