Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry, for example Windows NT for consumers, Windows Server for servers, and Windows IoT for embedded systems. Defunct Windows families include Windows 9x, Windows Mobile and Windows Phone.
The first version of Windows was released on November 20, 1985, as a graphical operating system shell for MS-DOS in response to the growing interest in graphical user interfaces (GUIs).
Windows is the most popular desktop operating system in the world, with 75% market share as of April 2022 according to StatCounter. However, Windows is not the most used operating system when including both mobile and desktop OSes, due to Android’s massive growth.
As of September 2022, the most recent version of Windows is Windows 11 for consumer PCs and tablets, Windows 11 Enterprise for corporations, and Windows Server 2022 for servers.
Microsoft, the developer of Windows, has registered several trademarks, each of which denotes a family of Windows operating systems that target a specific sector of the computing industry. As of 2014, the following Windows families were being actively developed:
- Windows NT: Started as a family of operating systems with Windows NT 3.1, an operating system for server computers and workstations. It now consists of three operating system subfamilies that are released almost at the same time and share the same kernel:
- Windows: The operating system for mainstream personal computers and tablets. The latest version is Windows 11. The main competitor of this family is macOS by Apple for personal computers and iPadOS and Android for tablets (c.f. Usage share of operating systems § Market share by category).
- Windows Server: The operating system for server computers. The latest version is Windows Server 2022. Unlike its client sibling, it has adopted a strong naming scheme. The main competitor of this family is Linux. (c.f. Usage share of operating systems § Market share by category)
- Windows PE: A lightweight version of its Windows sibling, meant to operate as a live operating system, used for installing Windows on bare-metal computers (especially on many computers at once), recovery or troubleshooting purposes. The latest version is Windows PE 10.
- Windows IoT (previously Windows Embedded): Initially, Microsoft developed Windows CE as a general-purpose operating system for every device that was too resource-limited to be called a full-fledged computer. Eventually, however, Windows CE was renamed Windows Embedded Compact and was folded under Windows Compact trademark which also consists of Windows Embedded Industry, Windows Embedded Professional, Windows Embedded Standard, Windows Embedded Handheld and Windows Embedded Automotive.
The following Windows families are no longer being developed:
- Windows 9x: An operating system that targeted the consumer market. Discontinued because of suboptimal performance. (PC World called its last version, Windows Me, one of the worst products of all time.) Microsoft now caters to the consumer market with Windows NT.
- Windows Mobile: The predecessor to Windows Phone, it was a mobile phone operating system. The first version was called Pocket PC 2000; the third version, Windows Mobile 2003 is the first version to adopt the Windows Mobile trademark. The last version is Windows Mobile 6.5.
- Windows Phone: An operating system sold only to manufacturers of smartphones. The first version was Windows Phone 7, followed by Windows Phone 8, and Windows Phone 8.1. It was succeeded by Windows 10 Mobile, which is now also discontinued.
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Early versions
Windows 1.0, the first version, released in 1985The history of Windows dates back to 1981 when Microsoft started work on a program called “Interface Manager”. It was announced in November 1983 (after the Apple Lisa, but before the Macintosh) under the name “Windows”, but Windows 1.0 was not released until November 1985. Windows 1.0 was to compete with Apple’s operating system, but achieved little popularity. Windows 1.0 is not a complete operating system; rather, it extends MS-DOS. The shell of Windows 1.0 is a program known as the MS-DOS Executive. Components included Calculator, Calendar, Cardfile, Clipboard Viewer, Clock, Control Panel, Notepad, Paint, Reversi, Terminal and Write. Windows 1.0 does not allow overlapping windows. Instead all windows are tiled. Only modal dialog boxes may appear over other windows. Microsoft sold as included Windows Development libraries with the C development environment, which included numerous windows samples.
Windows 2.0 was released in December 1987, and was more popular than its predecessor. It features several improvements to the user interface and memory management. Windows 2.03 changed the OS from tiled windows to overlapping windows. The result of this change led to Apple Computer filing a suit against Microsoft alleging infringement on Apple’s copyrights (eventually settled in court in Microsoft’s favor in 1993).Windows 2.0 also introduced more sophisticated keyboard shortcuts and could make use of expanded memory.
Windows 2.1 was released in two different versions: Windows/286 and Windows/386. Windows/386 uses the virtual 8086 mode of the Intel 80386 to multitask several DOS programs and the paged memory model to emulate expanded memory using available extended memory. Windows/286, in spite of its name, runs on both Intel 8086 and Intel 80286 processors. It runs in real mode but can make use of the high memory area.
In addition to full Windows-packages, there were runtime-only versions that shipped with early Windows software from third parties and made it possible to run their Windows software on MS-DOS and without the full Windows feature set.
The early versions of Windows are often thought of as graphical shells, mostly because they ran on top of MS-DOS and use it for file system services.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. Windows implemented an elaborate, segment-based, software virtual memory scheme, which allows it to run applications larger than available memory: code segments and resources are swapped in and thrown away when memory became scarce; data segments moved in memory when a given application had relinquished processor control.