Windows 10 is a series of operating systems developed by Microsoft and released as part of its Windows NT family of operating systems. It is the successor to Windows 8.1, released nearly two years earlier, and was released to manufacturing on July 15, 2015, and broadly released for the general public on July 29, 2015.

Microsoft initially aimed to have Windows 10 installed on over a billion devices within three years of its release; that goal was ultimately reached almost five years later on March 16, 2020. By January 2018, Windows 10 surpassed Windows 7 as the most popular version of Windows worldwide; and by May 2020, Windows 10 surpassed Windows 7 as the most popular version of Windows in China.As of October 2020, it is estimated that 75% of Windows PCs are running Windows 10, with that figure being 58% of all PCs (including Mac/Linux) and 27% of all devices (including mobile, tablet and console).