Windows XP, an out-of-date operating system Microsoft released back in 2001, is being cut off from official support as of today. That doesn’t mean the millions of systems still running it will stop working—but they could become more vulnerable to hacks over time.

Microsoft has set up a site for those seeking help with advice on taking the next steps. That means upgrading to Windows 7 or 8—or buying a new computer with those systems installed. One incentive to upgrade to the latest software: An update toWindows 8.1 promised in February becomes available today.

The Importance Of Being Stable

Windows XP remains widespread because it was a breakthrough for its time, the first mainstream operating system from Microsoft to run on a modern software kernel—the same kernel, or core of the operating system, that now powers all versions of Windows.

Its successor, Windows Vista, was widely panned, so many businesses never bothered to upgrade. And in countries throughout the developing world, it is widely pirated—in part because it runs well on older computer hardware available there.

Familiarity breeds sentimentality, which moved some users to poetry—like Errol Masters, who gave this eloquent Twitter sendoff:

The end of XP was bittersweet for Beacham McDougald, who posted her take on Facebook about how much money the move was costing her company:

Like Masters, Pete Morgan was a fan of Windows XP. He ranked Microsoft’s releases as follows:

Twitter user Run TMC thought of the hackers:

And Milan Vlasak felt a disturbance:

For more context, here’s ReadWrite editor-in-chief Owen Thomas discussing Windows XP with CCTV:

Photo by Dan Rowinski for ReadWrite