1985
First Windows release
1B+
Active Windows devices
NT
Kernel all versions share
14+
Major consumer versions
// DOS-Based Era (1981–1994)
1981
MS-DOS 1.0
Ships with the IBM PC. Text-only, single-user, single-task. Foundation for all early Windows versions.
Nov 20, 1985
Windows 1.0
First GUI shell on MS-DOS. Tiled (non-overlapping) windows. Poorly received but historically pivotal. Sold 500,000 copies by 1987.
1987
Windows 2.0
Overlapping windows. First support for Microsoft Word and Excel. Still a DOS shell, not a full OS.
1990
Windows 3.0
First commercial success — 4M copies in year one. Program Manager, virtual memory, improved fonts, multimedia support.
Breakthrough1992
Windows 3.1
TrueType fonts, drag-and-drop. The DOS-era peak before the NT transition.
// NT / 32-bit Era (1993–2001)
1993
Windows NT 3.1
Hybrid kernel, HAL layer, preemptive multitasking, security model. Foundation of ALL modern Windows. First true enterprise OS from Microsoft.
Kernel FoundationAug 24, 1995
Windows 95
Start menu, taskbar, long filenames, 32-bit apps. Sold 7M copies in 5 weeks. Defines the modern desktop paradigm. Cultural phenomenon.
Cultural Icon1998
Windows 98
USB support, FAT32, Internet Explorer 4 integration. Active Desktop for web-like UI. First consumer Windows with USB Plug and Play.
2000
Windows 2000
NT 5.0 for business. Active Directory, Group Policy, EFS encryption. Rock-solid enterprise foundation.
2000
Windows ME
Millennium Edition — last DOS-based consumer Windows. Notorious for instability. Quickly replaced.
Often Criticized
// Unified Platform Era (2001–2012)
Oct 2001
Windows XP
Merges consumer and NT lines. Luna UI, ClearType fonts, fast user switching. 240M sales in first year. Ran in production for 12+ years.
Most BelovedJan 2007
Windows Vista
Aero Glass UI, UAC security, new search. Criticized for hardware demands and driver incompatibility.
Poorly ReceivedOct 2009
Windows 7
Vista refined. Faster, redesigned taskbar, better hardware support. Fastest-selling OS at launch. Widely considered the best of the pre-Metro era.
Fan FavoriteOct 2012
Windows 8 / 8.1
Metro UI for touchscreens, removed Start menu. Enterprise users reacted negatively. 8.1 restored some familiar elements.
Divisive
// Modern Era (2015–Present)
Jul 2015
Windows 10
Start menu returns. Free upgrade for Win7/8.1. WSL, Cortana, Edge, DirectX 12. Bi-annual updates. 1B+ devices at peak.
Widespread AdoptionOct 2021
Windows 11
Centered taskbar, rounded corners, Snap Layouts, TPM 2.0 required. WSL2, DirectStorage, Auto HDR, Copilot AI (2023).
Current
// NT Architecture Stack
User Applications · Win32 API (kernel32.dll, user32.dll) · .NET / UWP
Environment Subsystems · ntdll.dll · System Call Interface (SYSCALL)
NT Executive · Memory Manager · I/O Manager · Security Monitor · Process Manager
NT Micro-Kernel · Thread Scheduling · Interrupt Handling · CPU Abstraction
Hardware Abstraction Layer (HAL) · CPU / Chipset / Bus / Timer normalization