Windows XP is arguably the most beloved version of Windows, hence why the legacy OS is still in use today on some PCs, albeit not nearly as many as in its heyday. That said, extended support has finally come to an end for the last supported version of Windows that was based on Windows XP.
That would be Windows Embedded POSReady 2009. Designed for point-of-sale devices, this is not the same OS that most users remember, dating back to before Vista, Windows 7, Windows 8/8.1, and now Windows 10. However, it runs the Windows XP kernel at its core.
As noted by TechRepublic, extended support for the defunct OS ended this past Tuesday, which officially puts a fork in the Windows NT 5.1 product family. Impressively, Windows XP's run lasted 17 years, 7 months, and 16 days.
Windows XP has enjoyed the longest run of any Windows OS ever. It's possible that Windows 10 will break the streak, now that Microsoft is no longer releasing monolithic upgrades every few years. But it has a long, long way to go.
What about Windows XP Home and Professional? Support ended for those main desktop variants back in April 2014. Nevertheless, there are still some machines that are clinging to the legacy OS. According to StatCounter, Windows XP accounts for 1.74 percent of all Windows machines, which puts it ahead of Vista.
If you expand the scope to include all desktop OSes and not just Windows, Netmarketshare has Windows XP accounting for 3.72 percent of all desktops in the world.
RIP, Windows XP.