Windows operating system and the evolution of Microsoft technology

Windows is a graphical operating system family and the evolution created by Microsoft technology that controls every layer of the modern PC, from the bootloader to the desktop. First released on 20 November 1985, it replaced MS-DOS command lines with movable windows, icons and a mouse-driven cursor, launching a software ecosystem that today exceeds 1.5 billion active machines.
Each generation introduced signature technologies: Windows 95 unified the 32-bit kernel with the Start menu and Plug-and-Play hardware detection; Windows XP merged consumer and business code bases, selling 400 million copies in five years; Windows 7 added jump-lists, libraries and touch primitives that prepared the OS for tablets; Windows 10 moved the platform to a rolling-release model with biometric login, DirectX 12 Ultimate graphics, and the Windows Subsystem for Linux that lets developers run ELF binaries natively; Windows 11 refines the UI with centered layouts, AI-driven widgets, and hardware-enforced security via TPM 2.0 and Secure Boot.

Under the hood the NT kernel schedules threads across multiple CPU cores, manages virtual memory through a page-table hierarchy, and isolates drivers in executive layers to prevent crashes. The Win32 and newer UWP APIs expose more than 75 000 callable functions, giving software access to file systems (NTFS, ReFS, FAT32), networking stacks (TCP, UDP, QUIC), and multimedia pipelines that deliver 4 K HDR video at 120 Hz. Enterprise features include BitLocker encryption, Hyper-V virtualization, Group Policy governance and Azure Active Directory cloud identity, tools that keep 96 % of Fortune 500 companies on Windows. Monthly cumulative patches, machine-learning antivirus and Microsoft Defender SmartScreen filter protect users from 18 billion authentic phishing sites every month, while backward compatibility allows 30-year-old 16-bit installers to run on 64-bit silicon through WOW emulation.