It is the successor to Windows 81 and was released for production on July 15, 2015
Windows 10 Pro Overview Windows 10 is a series of personal computer operating systems produced by Microsoft as part of the Windows NT family of operating systems.
and for retail sale on July 29, 2015
Windows 10 receives new versions on an ongoing basis, which are available at no additional cost to users.
One of the most notable features of Windows 10 is support for Universal Apps, an extension of the Metro-style apps first introduced in Windows 8
Devices in enterprise environments may receive these updates at a slower pace or use long-term support stages that receive only critical updates, such as security fixes, during their ten-year extended support life.
Universal apps can be designed to run across multiple Microsoft product families with nearly identical code—including computers, tablets, smartphones, embedded systems, Xbox One, Surface Hub and mixed reality
The Windows user interface has been redesigned to handle transitions between a mouse-centric interface and a touchscreen-optimized interface based on available input devices—especially on 2-in-1 PCs, and both interfaces include an updated menu Start, which combines elements of the traditional Windows 7 Start menu with the tiles of Windows 8.