Windows 10 is a major release of Microsoft's Windows NT operating system. It is the direct successor to Windows 8.1, which was released nearly two years earlier. It was released to manufacturing on July 15, 2015, and later to retail on July 29, 2015. Windows 10 was made available for download via MSDN and TechNet, as a free upgrade for retail copies of Windows 8 and Windows 8.1 users via the Windows Store, and to Windows 7 users via Windows Update. Windows 10 receives new builds on an ongoing basis, which are available at no additional cost to users, in addition to additional test builds of Windows 10, which are available to Windows Insiders. Devices in enterprise environments can receive these updates at a slower pace, or use long-term support milestones that only receive critical updates, such as security patches, over their ten-year lifespan of extended support. In June 2021, Microsoft announced that mainstream support for Windows 10 editions which are not in the Long-Term Servicing Channel (LTSC) ended on October 13, 2020 and extended support will end on October 14, 2025.Windows 10 received generally positive reviews upon its original release. Critics praised Microsoft's decision to provide the desktop-oriented interface in line with previous versions of Windows, contrasting the tablet-oriented approach of Windows 8, although Windows 10's touch-oriented user interface mode was criticized for containing regressions upon the touch-oriented interface of its predecessor. Critics also praised the improvements to Windows 10's bundled software over Windows 8.1, Xbox Live integration, as well as the functionality and capabilities of the Cortana personal assistant and the replacement of Internet Explorer with Microsoft Edge. However, media outlets have been critical of the changes to operating system behaviors, including mandatory update installation, privacy concerns over data collection performed by the OS for Microsoft and its partners, and adware-like tactics used to promote the operating system on its release.Microsoft initially aimed to have Windows 10 installed on over one billion devices within three years of its release; that goal was ultimately reached almost five years after release on March 16, 2020. By January 2018, Windows 10 surpassed Windows 7 as the most popular version of Windows worldwide. As of August 2022, Windows 10 is estimated to have a 72% share of Windows PCs, still 6.2 the share of its successor Windows 11 (and 6.0 of Windows 7). The share has been declining from a January 2022 peak of 82%, since Windows 11, which is now the second most popular Windows version in many countries. Windows 10 has a 58% share of all PCs (the rest being other Windows editions and other operating systems such as macOS and Linux), and a 22% share of all devices (including mobile, tablet and console) are running Windows 10. On June 24, 2021, Microsoft announced Windows 10's successor, Windows 11, which was released on October 5, 2021.Windows 10 is the final version of Windows which supports 32-bit processors (IA-32 and ARMv7-based) and devices with BIOS firmware. Its successor, Windows 11, requires a device that uses UEFI firmware and a 64-bit processor in any supported architecture (x86-64 for x86 and ARMv8 for ARM).

Microsoft Corporation is an American multinational technology corporation which produces computer software, consumer electronics, personal computers, and related services. Its best-known software products are the Microsoft Windows line of operating systems, the Microsoft Office suite, and the Internet Explorer and Edge web browsers. Its flagship hardware products are the Xbox video game consoles and the Microsoft Surface lineup of touchscreen personal computers. Microsoft ranked No. 21 in the 2020 Fortune 500 rankings of the largest United States corporations by total revenue; it was the world's largest software maker by revenue as of 2016. It is one of the Big Five American information technology companies, alongside Google, Amazon, Apple, and Meta.

Microsoft (the word being a portmanteau of "microcomputer software") was founded by Bill Gates and Paul Allen on April 4, 1975, to develop and sell BASIC interpreters for the Altair 8800. It rose to dominate the personal computer operating system market with MS-DOS in the mid-1980s, followed by Microsoft Windows. The company's 1986 initial public offering (IPO), and subsequent rise in its share price, created three billionaires and an estimated 12,000 millionaires among Microsoft employees. Since the 1990s, it has increasingly diversified from the operating system market and has made a number of corporate acquisitions, their largest being the acquisition of LinkedIn for $26.2 billion in December 2016, followed by their acquisition of Skype Technologies for $8.5 billion in May 2011.As of 2015, Microsoft is market-dominant in the IBM PC compatible operating system market and the office software suite market, although it has lost the majority of the overall operating system market to Android. The company also produces a wide range of other consumer and enterprise software for desktops, laptops, tabs, gadgets, and servers, including Internet search (with Bing), the digital services market (through MSN), mixed reality (HoloLens), cloud computing (Azure), and software development (Visual Studio).

Steve Ballmer replaced Gates as CEO in 2000, and later envisioned a "devices and services" strategy. This unfolded with Microsoft acquiring Danger Inc. in 2008, entering the personal computer production market for the first time in June 2012 with the launch of the Microsoft Surface line of tablet computers, and later forming Microsoft Mobile through the acquisition of Nokia's devices and services division. Since Satya Nadella took over as CEO in 2014, the company has scaled back on hardware and has instead focused on cloud computing, a move that helped the company's shares reach its highest value since December 1999.Earlier dethroned by Apple in 2010, in 2018 Microsoft reclaimed its position as the most valuable publicly traded company in the world. In April 2019, Microsoft reached the trillion-dollar market cap, becoming the third U.S. public company to be valued at over $1 trillion after Apple and Amazon respectively. As of 2020, Microsoft has the third-highest global brand valuation.