Windows is the most popular desktop operating system in the world, with a 70% market share as of March 2023[update], according to StatCounter;[13] however when including mobile OSes, it is not the most used, in favor of Android.

These products are generally categorized as follows: The history of Windows dates back to 1981 when Microsoft started work on a program called "Interface Manager".

Components included Calculator, Calendar, Cardfile, Clipboard Viewer, Clock, Control Panel, Notepad, Paint, Reversi, Terminal and Write.

The early versions of Windows are often thought of as graphical shells, mostly because they ran on top of MS-DOS and used it for file system services.

[23] However, even the earliest Windows versions already assumed many typical operating system functions; notably, having their own executable file format and providing their own device drivers (timer, graphics, printer, mouse, keyboard and sound).

Unlike MS-DOS, Windows allowed users to execute multiple graphical applications at the same time, through cooperative multitasking.

[28] Windows 3.2 was generally sold by computer manufacturers with a ten-disk version of MS-DOS that also had Simplified Chinese characters in basic output and some translated utilities.

While still remaining MS-DOS-based, Windows 95 introduced support for native 32-bit applications, plug and play hardware, preemptive multitasking, long file names of up to 255 characters, and provided increased stability over its predecessors.

[34] However, Windows Me was faced with criticism for its speed and instability, along with hardware compatibility issues and its removal of real mode DOS support.

NT OS/2 was intended to be a secure, multi-user operating system with POSIX compatibility and a modular, portable kernel with preemptive multitasking and support for multiple processor architectures.

Home and Professional were later accompanied by the "Media Center" edition (designed for home theater PCs, with an emphasis on support for DVD playback, TV tuner cards, DVR functionality, and remote controls), and the "Tablet PC" edition (designed for mobile devices meeting its specifications for a tablet computer, with support for stylus pen input and additional pen-enabled applications).

After a lengthy development process, Windows Vista was released on November 30, 2006, for volume licensing and January 30, 2007, for consumers.

[43] Windows 7 has multi-touch support, a redesigned Windows shell with an updated taskbar with revealable jump lists that contain shortcuts to files frequently used with specific applications and shortcuts to tasks within the application,[44] a home networking system called HomeGroup,[45] and performance improvements.

A number of significant changes were made on Windows 8, including the introduction of a user interface based around Microsoft's Metro design language with optimizations for touch-based devices such as tablets and all-in-one PCs.

These changes include the Start screen, which uses large tiles that are more convenient for touch interactions and allow for the display of continually updated information, and a new class of apps which are designed primarily for use on touch-based devices.

The new Windows version required a minimum resolution of 1024×768 pixels,[46] effectively making it unfit for netbooks with 800×600-pixel screens.

The new service will allow for cross-platform usage, aiming to make the operating system available for both Apple and Android users.

The new service is an attempt at capitalizing on the growing trend, fostered during the COVID-19 pandemic, for businesses to adopt a hybrid remote work environment, in which "employees split their time between the office and home".

Windows NT 4.0 and its predecessors supported PowerPC, DEC Alpha and MIPS R4000 (although some of the platforms implement 64-bit computing, the OS treated them as 32-bit).

The OEMs and device makers can modify and create their own user interfaces and experiences, while Windows CE provides the technical foundation to do so.

[citation needed] Microsoft had begun to integrate Git into Team Foundation Server in 2013,[80] but Windows (and Office) continued to rely on Source Depot.

[56][82][83] Because of its large, decades-long history, however, the Windows codebase is not especially well suited to the decentralized nature of Linux development that Git was originally created to manage.

[citation needed] Microsoft has been working on a new project called the Virtual File System for Git (VFSForGit) to address these challenges.

[93] Including personal computers of all kinds (e.g., desktops, laptops, mobile devices, and game consoles), Windows OSes accounted for 32.67% of usage share in August 2021, compared to Android (highest, at 46.03%), iOS's 13.76%, iPadOS's 2.81%, and macOS's 2.51%, according to Net Applications[94] and 30.73% of usage share in August 2021, compared to Android (highest, at 42.56%), iOS/iPadOS's 16.53%, and macOS's 6.51%, according to StatCounter.

[104] When logging in as a standard user, a logon session is created and a token containing only the most basic privileges is assigned.

User applications, including the Windows shell, are then started with the restricted token, resulting in a reduced privilege environment even under an Administrator account.

[105] Leaked documents from 2013 to 2016 codenamed Vault 7 detail the capabilities of the CIA to perform electronic surveillance and cyber warfare,[106] such as the ability to compromise operating systems such as Windows.

In July 2024, Microsoft signalled an intention to limit kernel access and improve overall security, following a highly publicised CrowdStrike update that caused 8.5 million Windows PCs to crash.

This system varies from other vendor products such as Linux and NetWare due to the 'static' allocation of permission being applied directly to the file or folder.

It can allow someone to run any command on the lock screen, including making themselves administrator, just by changing the name of cmd to one of those two programs.