Thirty years ago, on 20 November 1985, Microsoft released Windows 1.0, the firm's first attempt at offering a graphical user environment for personal computers. Although it got off to a faltering start, the platform went on to become the dominant operating system for using computers, but is now facing its greatest challenge to stay relevant in the era of mobile devices and the cloud.
Few computing platforms have managed to survive for three decades, and it is difficult to overestimate the impact that Windows has had on the IT landscape during that time. But the Windows of today bears little relation to that first release, and looks set to transform even further to meet future challenges.
Windows 1.0 wasn't even an operating system - it was just a graphical user interface (GUI) for personal computers running Microsoft's prosaically named disk operating system. It's primitive by today's standards, but enabled users to point and click at on-screen controls with a mouse instead of typing into a command line interface.
The future for Windows looked unpromising. A year earlier, in 1984, Apple had launched the Macintosh, a computer designed from the ground up around the combination of the mouse and GUI. Compared with the Mac, a PC running Windows looked slow and clunky, a situation that was to persist for many years.
Microsoft's advantage was that the PC was already being widely adopted by businesses for everyday work processes, and was already accumulating an ecosystem of applications and software vendors. In contrast, Apple tended to focus on the Mac's superior graphics, and its platform was increasingly seen as being for tasks such as desktop publishing and design.
But Windows really started to gain traction with version 3.0 in 1990, which introduced a much improved user interface and made better use of memory management capabilities in newer Intel processors. It gained its dominant position in the desktop operating system market with Windows 95, which ushered in a user interface that's still recognisable today.
However, current versions of Windows can trace their origins back to a project to develop a full 32-bit 'professional' operating system. The result was Windows NT, launched in 1993, which first introduced the Win32 APIs.
Microsoft merged the consumer and professional flavours of Windows with XP, which launched in 2001, blending the multimedia and graphics support of the Windows 9.x family with the Windows NT kernel and a slightly revamped user interface.
Windows XP turned out to be the most successful version of Windows to date, and is still used by many people and organisations around the world, despite hitting the end of its lifecycle last year and becoming unsupported by Microsoft.
XP's longevity can be attributed partly to a lacklustre successor, Windows Vista, which attempted to fix the security problems that had dogged XP. However, this led to changes that broke compatibility with some applications and irked users, and Vista's hardware requirements were relatively steep for the time. Consequently, Vista uptake was slow when it was released in 2006.
Microsoft took the criticism of Vista to heart, and ironed out pretty much all of the kinks with the launch of Windows 7 in 2009, introducing a refreshed user interface that has stood the test of time and leading to wide acceptance of the platform.
The history of Windows - and Microsoft itself - has been punctuated by a series of misfires, in which the company has taken its eye off the ball or seemingly been too preoccupied with its internal conversations to pay attention to what people wanted.
The first of these was arguably Microsoft's failure to spot the rapid ascendancy of the web in the 1990s, such that Windows 95 shipped without a web browser. The firm rapidly fixed this with the release of Internet Explorer, based on a reworked version of Spyglass Mosaic.
Another was Microsoft's overreaction to the success of the Apple iPad. Faced with many consumers opting to buy an iPad rather than a new PC, Microsoft decided that the next version of Windows had to be able to outdo the iPad, which ran essentially the same platform as Apple's iPhone.
The result was Windows 8, which introduced a radical new tile-based user interface designed for touchscreen input, and relegated the existing back catalogue of Windows applications to a separate 'legacy' desktop environment, hidden away behind a tile on the main screen.
Windows 8 has also been met with a rather mixed response since its launch in 2012, and it's fair to say that it simply has not been as successful as Microsoft would have liked. Others went further, and pointed the finger at Windows 8 for sluggish sales of PCs following its release.
Fortunately, Microsoft seems to have taken note, and the current Windows 10 release has had a broadly favourable reception since its official launch in July 2015. Research firm Forrester even published a report indicating that half of all enterprise firms expect to upgrade to the new operating system by the end of 2016.
Windows 10 has placated users by putting the familiar Start menu and desktop environment centre stage, but keeping and extending the touch-centric support introduced with Windows 8 and even integrating the live tiles and apps with the Start menu.
Microsoft has also moved to a more fluid delivery model with Windows 10, which will have updates and even new functionality delivered on a regular basis via the Windows Update mechanism, an approach that has been dubbed 'Windows-as-a-service'.
Windows 10 also sees Microsoft attempting to converge the PC with other platforms, such as Windows Phone and even embedded systems, to create a kind of unified ecosystem. While not running the same operating system or identical user interfaces, Microsoft intends there to be common APIs and common applications.
The 30th anniversary of Windows thus sees Microsoft with a very different platform than the one it started out with, one intended to work on a variety of platforms and devices and, with today's connected world, offering access to capabilities virtually unthinkable back then.
However, the ultimate goal remains that of helping the end user to be more productive, and to be able to do what they want to do as simply and effortlessly as possible.
For the future, a lot is riding on the success of Microsoft's cross-platform strategy for Windows 10, and whether the firm can drum up developer support behind its new-style APIs in order to make a transition away from the desktop-style Win32 applications that are still the most widely used.
There has been speculation that Windows 10 could be the last version of Windows. However, this doesn't imply that Windows will cease to exist, but that the continual update method means there may be no monolithic new version launches in future.
But there continues to be the threat of alternative platforms and devices, such as Apple's new iPad Pro which is being pitched as a laptop replacement, and with PC shipments continuing to slide, the 30th anniversary of Windows heralds an uncertain future.
See what we wrote about Windows on its 25th anniversary
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