Which Windows version was first to use the NT kernel for consumers?

Windows XP was the first consumer Windows version to use the Windows NT kernel. Before XP, Microsoft maintained two main desktop families: the consumer Windows 95/98/Me line, built around MS-DOS and the Windows 9x architecture, and the more robust Windows NT line, aimed mainly at businesses and professionals.

Windows 2000 already used the NT kernel, but it was marketed as a business operating system rather than a mainstream consumer edition. Windows XP, released for retail on October 25, 2001, unified the consumer and business lines under one NT-based platform. Its consumer editions inherited NT's improved security, stability, memory protection, and preemptive multitasking.

A common mix-up is Windows 2000: it came first chronologically, but it was not the consumer Windows successor to Windows Me. XP replaced Windows Me for home users while also succeeding Windows 2000 in the professional market. Later consumer releases, including Vista, Windows 7, and Windows 10, continued the NT-based design.