Windows 10, released in July 2015 by Microsoft. Notable features include the return of the Start Menu, introduction of the virtual assistant Cortana, Universal Windows Platform for cross-device app development, Continuum for adaptive interface, and the Microsoft Edge browser. Windows 10 emphasizes security with features like Windows Defender and BitLocker. The operating system follows a “Windows as a Service” model, providing regular feature updates. Microsoft offered a free upgrade to Windows 10 for eligible Windows 7 and 8.1 users.