Microsoft Windows

operating system
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Also known as: Windows OS
Also called:
Windows and Windows OS
Key People:
Alan Kay

Microsoft Windows, computer operating system (OS) developed by Microsoft Corporation to run personal computers (PCs). Featuring the first graphical user interface (GUI) for IBM-compatible PCs, the Windows OS soon dominated the PC market. Approximately 90 percent of PCs run some version of Windows.

The first version of Windows, released in 1985, was simply a GUI offered as an extension of Microsoft’s existing disk operating system, or MS-DOS. Based in part on licensed concepts that Apple Inc. had used for its Macintosh System Software, Windows for the first time allowed DOS users to visually navigate a virtual desktop, opening graphical “windows” displaying the contents of electronic folders and files with the click of a mouse button, rather than typing commands and directory paths at a text prompt.

Subsequent versions introduced greater functionality, including native Windows File Manager, Program Manager, and Print Manager programs, and a more dynamic interface. Microsoft also developed specialized Windows packages, including the networkable Windows for Workgroups and the high-powered Windows NT, aimed at businesses. The 1995 consumer release Windows 95 fully integrated Windows and DOS and offered built-in Internet support, including the Web browser Internet Explorer.

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With the 2001 release of Windows XP, Microsoft united its various Windows packages under a single banner, offering multiple editions for consumers, businesses, multimedia developers, and others. Windows XP abandoned the long-used Windows 95 kernel (core software code) for a more powerful code base and offered a more practical interface and improved application and memory management. The highly successful XP standard was succeeded in late 2006 by Windows Vista, which experienced a troubled rollout and was met with considerable marketplace resistance, quickly acquiring a reputation for being a large, slow, and resource-consuming system. Responding to Vista’s disappointing adoption rate, Microsoft in 2009 released Windows 7, an OS whose interface was similar to that of Vista but was met with enthusiasm for its noticeable speed improvement and its modest system requirements.

Windows 8 in 2012 offered a start screen with applications appearing as tiles on a grid and the ability to synchronize settings so users could log on to another Windows 8 machine and use their preferred settings. In 2015 Microsoft released Windows 10, which came with Cortana, a digital personal assistant like Apple’s Siri, and the Web browser Microsoft Edge, which replaced Internet Explorer.

The same year that Windows 10 was released, a developer at the Microsoft Ignite conference offhandedly announced that Windows 10 would be the “last” version of Windows. However, Microsoft later clarified that the company would regularly update the OS but that there would be no more large-scale revisions.

In 2021 Microsoft released Windows 11, which features a redesigned start menu and faster operating speeds. However, Cortana was removed from the OS because its performance lagged behind virtual assistant competitors such as Siri and Amazon’s Alexa. Cortana was replaced, in some senses, by a new generative artificial intelligence (AI) feature known as Copilot, which uses large language models to generate content in an effort to improve productivity. The software, which uses the technology popularized by ChatGPT and Google Gemini, responds to user commands (for example, “create a budgeting spreadsheet”) by generating new content and is integrated into applications such as Microsoft 365 (which includes Microsoft Word and PowerPoint, among others), Bing, and the Windows task bar.

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Windows 11 has encountered resistance from those who had been using Windows 10, and the majority of Windows users continue to use the prior OS. Users are especially critical of the newly redesigned start menu, which features less flexible options than the previous OS and lacks the older version’s “live tiles” feature, which pulled information and news in real time from the Internet. The feature was replaced by a widgets dashboard separate from the start menu. Additionally, the task bar in Windows 11 is centered at the bottom of the computer screen, although it can be aligned to the bottom left (its default position in Windows 10). Many users thought that this limited the flexibility of the OS and chose not to upgrade. Windows 11 also requires PCs to run on a 64-bit processor, so users with 32-bit processors cannot use the new OS unless they purchase a new computer. Although Windows has not formally announced the release of a new OS version, rumors have abounded regarding a 2024 update.

The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Tara Ramanathan.