Microsoft has announced an extension of Windows 10 support until October 2026 at no additional cost, affecting approximately 400 million users. This extension was previously set to end in October 2025. Users with eligible PCs for an upgrade number around 400 million, while about 240 million are not eligible. The extension includes Security Intelligence Updates for Microsoft Defender Antivirus on Windows 10 through October 2028, but it is a one-year arrangement and not full security support. Users can enroll in the Extended Security Updates (ESU) program through options like cloud backup, reward points, or a fee, and this feature will be available to all users in the coming weeks.