More than a dozen years after it first went on sale, the reign of Windows XP is finally coming to an end.
XP was Microsoft's most popular operating system ever — it was only recently overtaken by Windows 7 as the most used OS in the world – and it's still running on somewhere around a quarter of all desktops.
As of next week however, XP is no longer supported by Microsoft: no more software updates or security patches will be forthcoming from the company.
XP's dozen-year lifespan is the equivalent of millennia in tech years, and so XP is a digital dinosaur still roaming the earth. Many will be mourning its passing, others will be grumbling as they scramble to update to a new operating system, and some will be cursing because they have to pay out for additional support after having left their migration too late.
But the death of XP is more than just a headache (and the cause of some heartache) for IT: it also part of some profound changes in the tech landscape.
As we lay XP is to rest, we're also saying goodbye to some of technology's old certainties: that the PC is the default hardware for the average user, that Windows is the standard operating system it will run. Both of those assumptions held true throughout the life of XP — but no longer.
The decline of the PC continues: it's already been overtaken by tablets and smartphones among consumers, and increasing in business. As well as the rise of new hardware form factors, new operating systems are grabbing market share too: in the case of tablets and smartphones, it's still pretty much a two horse race between Android cornering the mass market and iOS at the premium end.
Windows is still around of course, and still a strong presence (especially in business), but its dominance is being questioned: the upgrade from XP to Windows 8 is such a big leap that some may consider switching to an alternative platform altogether, such as iPads or Chromebooks.
All of this means we're entering a new era of fragmented computing, a jumble of devices, operating systems and competing ecosystems.
Neither Android nor iOS are monoliths: there are many versions of Android in use (less than 10 percent of devices are running KitKat, the latest iteration of the operating system), and the older versions of Apple's iPhone and iPad (only a few years old) cannot run the latest versions of iOS. Build it once, run anywhere is just as much of a dream as it ever was.
Competing ecosystems have lead to a profusion of app stores and operating systems flavours (just compare Amazon's Fire OS to Android) which can create strife for developers and users. Stifling walled gardens of content and apps are everywhere as tech companies seek to enforce the loyalty of their customers.
Windows, of course, was just another walled garden (ask the Linux enthusiasts or the Mac fans) but for most it was such a big enclosure that most couldn't see the walls.
None of this is bad, just different. It's unlikely that we'll see a platform as dominant as Windows again; Android is making a strong play but will probably never be the operating system of everything.
The downside of all of this is uncertainty and fragmentation, at least for now. But it's also a bigger, more complicated and more exciting world with better devices, wider options and more opportunity.
ZDNet's Monday Morning Opener is our opening salvo for the week in tech. As a global site, this editorial publishes on Monday at 8am AEST in Sydney, Australia, which is 6pm Eastern Time on Sunday in the US. It is written by a member of ZDNet's global editorial board, which is comprised of our lead editors across Asia, Australia, Europe, and the US.