Windows Versions

The 1980 IBM deal that funded everything

In August 1980, IBM came to Microsoft for an operating system to ship with the IBM PC. Microsoft didn't have one. It licensed (and the next year purchased outright) QDOS from Seattle Computer Products, rebranded it MS-DOS, and — this is the consequential part — retained the right to license it to other PC manufacturers. The non-exclusive clause is the single most important contract decision in PC history. When Compaq, Dell, and the rest of the clone industry took off, MS-DOS rode every machine.

Windows 1.0 in November 1985 ran on top of MS-DOS — initially a graphical shell rather than an OS in its own right. The Windows-on-DOS architecture would persist for the entire 9x line; the NT line, started in 1988 under Dave Cutler, was built from scratch on a different model. But the profit engine that funded NT's eight-year development was the DOS license fees Microsoft was collecting on every PC sold under that 1980 contract.

Apple v. Microsoft (1988–1994)

Apple Computer, Inc. v. Microsoft Corp. was filed in March 1988 after Windows 2.0 introduced overlapping windows. Apple alleged the new Windows UI infringed the look and feel of the Macintosh. The complication: Apple had previously licensed certain UI elements to Microsoft for Windows 1.0, and the question was how broadly that license extended.

Most of Apple's claims were dismissed; the case effectively concluded in Microsoft's favor in 1994 when the Ninth Circuit affirmed dismissal. The case is the foundational US precedent for the position that individual GUI elements are not protected by copyright — a ruling that would be cited for decades in every subsequent UI dispute.

The Windows 95 launch — August 24, 1995

The August 24, 1995 launch event was a multi-hour live broadcast hosted by Jay Leno on the Microsoft campus. The Rolling Stones' "Start Me Up" was used in the launch campaign — per USA v. Microsoft trial exhibits, the licensing fee was reportedly $3 million. Stores opened at midnight; lines wrapped around blocks. Windows 95 sold seven million copies in five weeks.

Bill Gates's "Internet Tidal Wave" memo of May 26, 1995 — less than three months earlier — was already reorienting Microsoft around the web. Gates had concluded that the internet would reshape every product category Microsoft was in, and the company needed to respond as if its survival depended on it. That memo became a public document via the antitrust trial exhibits. Windows 95 launched into a company already pivoting away from the model the launch had been designed to celebrate.

The parallel-line strategy (1993–2001)

For nearly a decade, Microsoft maintained two separate Windows kernel codebases: the DOS-derived 9x line (95, 98, 98 SE, ME) for consumers, and the from-scratch NT line (3.1, 3.5, 3.51, 4.0, 2000) for business. Each had its own driver model, its own filesystem story, and its own constituency. Reconciling them was the explicit goal of Windows 2000 (which couldn't run consumer games or DOS-era titles well enough to merge) and ultimately of Windows XP (which could).

Dave Cutler is the central engineer of this era. He was recruited from DEC in 1988 specifically to build a portable, secure, multi-user OS that would replace 9x once the consumer hardware caught up. Showstopper! by G. Pascal Zachary (1994) remains the canonical account of NT's development — the team's culture, the schedule pressure, the politics with Microsoft's other groups. Cutler stayed at Microsoft as a Senior Technical Fellow and continued to influence kernel work decades later.

The Halloween Documents (1998)

In late October and early November 1998, internal Microsoft strategic memos analyzing Linux as a competitive threat were leaked to Eric S. Raymond and posted publicly on catb.org. They became known as The Halloween Documents. It was the first time a major proprietary-software company's strategic anxiety about open-source was visible in its own words: the documents discussed FUD as a deliberate competitive strategy, the perceived robustness of Linux on commodity hardware, and ways to undermine open protocols by extending them with proprietary additions ("embrace, extend, extinguish"). The documents framed the next decade of Microsoft-vs.-Linux discourse and are still cited today.

United States v. Microsoft (1998–2002)

The DOJ filed suit against Microsoft on May 18, 1998, joined by twenty state attorneys general. The core allegation was that Microsoft used its Windows monopoly to crush Netscape Navigator by bundling Internet Explorer into Windows 95 and 98 at zero marginal cost — an act the DOJ argued was unlawful monopoly maintenance under Section 2 of the Sherman Act.

Bill Gates's videotaped deposition was widely viewed as catastrophic for Microsoft. Judge Thomas Penfield Jackson issued findings of fact in November 1999 and conclusions of law in April 2000 that were sweeping in their characterization of Microsoft's conduct. In June 2000, Jackson ordered Microsoft split into an operating-systems company and an applications company.

In June 2001, the D.C. Circuit Court of Appeals unanimously reversed the breakup remedy while upholding the monopoly-maintenance findings. The appeals court also chastised Jackson for press contacts during the trial, which had compromised the appearance of impartiality. The Bush DOJ settled with Microsoft in November 2001; the consent decree was approved in 2002 and ultimately expired in 2011. The EU Commission pursued parallel actions, including a 2004 Windows Media Player bundling decision (€497M fine), the 2009 browser-ballot-screen settlement, and a 2013 fine for breach of that ballot commitment.

USA v. Microsoft is the single most consequential antitrust action in software history and remains the right baseline against which to compare Epic v. Apple, the EU Digital Markets Act, and FTC v. Activision.

The Vista era (2003–2009)

"Longhorn" was originally pitched as a small release between XP and Blackcomb. It grew into a six-year megaproject built around an object-oriented filesystem (WinFS), a new presentation layer (Avalon, later WPF), and a new web-services-style communication stack (Indigo, later WCF). In 2004 the project was reset: most of the ambitious storage and presentation work was cut, and the codebase was rebooted on top of Windows Server 2003's. Vista shipped in January 2007 with much-reduced scope and a bruising launch.

Hardware partners had shipped "Vista Capable" stickers on systems that could run Vista's basic SKU but not the flagship Aero glass features — and many couldn't run Vista well at all. The Kelley v. Microsoft class action followed. UAC prompts were widely mocked, and Vista's reputation calcified before SP1 and SP2 fixed most of the actual problems.

The "Mojave Experiment" marketing campaign in 2008 had unwitting users review what they were told was a new OS code-named Mojave but was actually Vista. Reactions improved. By the time Windows 7 shipped two years later, Vista had become a cautionary tale at Microsoft for what happens when the product's ambition outruns the OEM and IHV ecosystem's readiness to support it.

The Ballmer era (2000–2014)

Steve Ballmer succeeded Bill Gates as CEO in January 2000. He oversaw the high-water mark of the desktop monopoly — XP, the antitrust survival, Office's continued dominance, the launch of Xbox, the transition to enterprise services — and most of the lowlights too: Vista, Windows Phone's failure to gain meaningful share, the Surface RT writedown of $900M in July 2013, and the Nokia acquisition for $7.2B in 2013 with most of it written off two years later.

In a January 2007 USA Today interview, Ballmer dismissed the iPhone within days of its announcement: "There's no chance that the iPhone is going to get any significant market share. No chance." The quote became one of the most-cited misreads of an emerging product in the modern era. Ballmer announced his retirement in August 2013; Satya Nadella took over in February 2014.

The Sinofsky era and Windows 8

Steven Sinofsky led the Windows division through Windows 7 (lauded for its discipline and the recovery from Vista) and Windows 8 (controversial). Windows 8's removal of the Start menu and its Metro / Modern UI fullscreen-tiles layout were a deliberate bet that touch and tablets were becoming the future of the PC, and that the desktop should compromise to make room for that future.

The bet didn't land for desktop users. Sinofsky departed Microsoft in November 2012, a few weeks after Windows 8's October 2012 launch. The Start menu returned in pieces in 8.1 (October 2013) and fully in Windows 10 (July 2015). Sinofsky's Hardcore Software Substack, running since 2021, has provided an unusually candid first-person account of the Windows 7 and Windows 8 development arcs.

The Surface and Windows-on-ARM saga

Surface RT, launched in October 2012 alongside Windows 8, was the failed first attempt at an ARM-based Windows tablet. It was locked to the curated Windows Store, incompatible with Win32 software, and shipped with a constrained Office build. It didn't sell. In July 2013, Microsoft took a $900 million writedown on Surface RT inventory.

ARM stayed largely dormant on Windows for nearly a decade. Surface Pro X (2019) reopened the door with a custom Microsoft SQ1/SQ2 chip; the 2024 Qualcomm Snapdragon X / Copilot+ PC wave revived it on a more competitive basis, with ARM-native versions of Office and most of the major creative apps. Windows 11 24H2 introduced an improved x86-on-ARM emulation layer (Prism) that materially closed the compatibility gap with native x64 Windows.

Windows Mobile / Phone retreat (2010–2017)

Windows Phone 7 (October 2010) reset the phone OS entirely, abandoning the older Windows Mobile codebase. The Nokia partnership announced in February 2011 was meant to reinvigorate Windows Phone as a hardware story; in 2013 Microsoft acquired Nokia's devices and services business outright for $7.2 billion. Andy Lees and Terry Myerson on the Microsoft side, Stephen Elop on the Nokia side, were the central figures across this arc.

The combined business never approached double-digit market share against iOS and Android. In July 2015 Microsoft announced an $7.6 billion writedown on the Nokia acquisition and roughly 7,800 layoffs, mostly in the former Nokia organization. Most of the residual handset business was sold or wound down by 2016. Windows 10 Mobile officially ended support in 2019.

Combined with the Surface RT writedown, the failed mobile bet cost Microsoft well over $10 billion. The Microsoft of 2014 onward concluded the platform fight at the OS layer was over and pivoted to building Microsoft software on iOS and Android instead — Office for iPad in March 2014 was the first signal of that strategic reorientation.

The Nadella era (2014–present)

Satya Nadella succeeded Steve Ballmer as CEO in February 2014. The defining strategic moves: declaring "cloud-first, mobile-first" and later "intelligent cloud + intelligent edge"; shipping Windows Subsystem for Linux in 2016 and WSL 2 in 2020; making PowerShell open-source and cross-platform; bringing .NET and TypeScript into the open-source mainstream; building Microsoft Office and Edge first-class on iOS and Android.

The acquisitions defined the era as much as the engineering moves: LinkedIn ($26.2B in 2016), GitHub ($7.5B in 2018), ZeniMax/Bethesda ($7.5B in 2021), Activision Blizzard ($68.7B in 2023). The OpenAI partnership, beginning in 2019 and now reportedly representing tens of billions in cumulative investment, reshaped Microsoft's product surface from Bing through GitHub Copilot through Microsoft 365 Copilot through Copilot+ PCs.

Nadella's Hit Refresh (2017) is the public articulation of the cultural reset that came with the strategic one. Windows became, increasingly, one surface of Microsoft rather than the company's center of gravity.

The Activision Blizzard acquisition (2022–2023)

Microsoft announced its acquisition of Activision Blizzard in January 2022 at $68.7 billion. It was the largest tech acquisition in history at the time. Antitrust scrutiny was intense and global: the FTC sought a preliminary injunction to block the deal, which was denied in July 2023; the UK Competition and Markets Authority initially blocked the deal in April 2023 over cloud-gaming concerns and conditionally cleared it in October 2023 after Microsoft restructured the deal to divest cloud-streaming rights to Ubisoft.

The deal closed on October 13, 2023. It reshaped Xbox's positioning — first-party titles like Call of Duty, World of Warcraft, and Diablo gave Microsoft Gaming a publisher catalog rivalling any in the industry — and the broader gaming industry's consolidation pattern.

People who actually shaped Windows

Bill Gates — founder; drove every release from 1.0 through Windows 2000; stepped down as CEO in January 2000 and as Chief Software Architect in June 2008. Paul Allen — cofounder; less direct Windows involvement after his 1983 Hodgkin's diagnosis and departure; his 2011 memoir Idea Man is the cofounder-perspective history; died October 2018. Steve Ballmer — CEO 2000–2014. Satya Nadella — CEO since February 2014.

On the engineering side: Dave Cutler — recruited from DEC in 1988, sometimes called "the father of NT," remained a Microsoft Senior Technical Fellow into recent years. Steven Sinofsky — Windows 7 / Windows 8 lead; left November 2012; now writing Hardcore Software on Substack. Jim Allchin — long-time Windows division head, retired around the Vista launch. Terry Myerson — Windows lead 2013–2018, oversaw Windows 10's launch and the mobile retreat. Panos Panay — Surface and Windows lead until September 2023, departed for Amazon. Pavan Davuluri — current EVP, Windows + Devices, since 2024. Charles Simonyi — long-time architect and the Hungarian-born father of WYSIWYG word processing. Jeffrey Snover — PowerShell, Windows Server.

Outside Microsoft, two beat reporters defined a generation of Windows coverage: Mary Jo Foley, longtime All About Microsoft author at ZDNet, and Paul Thurrott at Thurrott.com.

The sibling and derived OS family

Several OS lines branch off the main Windows tree:

• Windows Server — its own line, branched in 2003. See the combined row in the table.
• Windows CE → Windows Mobile → Windows Phone 7/8/8.1 → Windows 10 Mobile — the long-running mobile arc, now wound down.
• Windows IoT — still shipping; powers a large quiet base of embedded systems.
• Windows RT — the 8-era ARM-only build, locked to Windows Store apps. RIP.
• Xbox OS — runs as a Hyper-V partition on top of a Windows-derived host; quietly one of the most-deployed Windows-family installations on Earth.
• Windows Holographic / HoloLens — the AR/MR variant.
• Azure Stack HCI — on-prem hyperconverged variant of the server line.

Sibling pages under /data/windows/ — e.g. /data/windows/server-versions/, /data/windows/mobile/, /data/windows/antitrust-timeline/ — are the natural follow-ups to this page if any of the spun-off topics outgrow their summary here.