Windows 8, Microsoft's 2012 flop, will be retired from all support today, putting the 48 million users who still run the three-year-old operating system in a spot: Upgrade or risk getting hacked.

After today, Microsoft will no longer provide security updates for Windows 8 -- or for IE10 and IE11, the company browsers that run on the OS -- and the company will not offer technical support for the operating system.

To continue to receive security updates, Windows 8 users must upgrade to Windows 8.1, the free 2013 edition available from the Windows Store, Microsoft's app warehouse.

Today's support deadline has been in place since the debut of Windows 8.1 more than two years ago, and at the time was characterized by Microsoft as analogous to the 24-month grace period previously given to customers for migrating from a core OS to that operating system's first "service pack."

Although the service pack concept is now dead -- mugged by Windows 8 and murdered by Windows 10 -- Microsoft described the Windows 8-to-Windows 8.1 upgrade requirement in service pack terms when it launched the latter in October 2013.

There are significant numbers of devices running Windows 8, according to Web analytics vendor Net Applications. Last month, Net Applications estimated that Windows 8 powered 3% of all Windows personal computers, while the newer Windows 8.1 ran on about 11.3% of Windows PCs.

Using the 1.5 billion number that Microsoft claims as the total number of PCs which run Windows worldwide, Windows 8 was on approximately 48 million systems last month, Windows 8.1 on about 180 million.

Both those numbers were down from seven months ago, when Computerworld last reported on Windows 8's and 8.1's user share, a rough estimate of the number of the devices running the OS. In mid-June, Windows 8 powered 63 million machines, Windows 8.1 226 million.

Windows 8 still powers more than 1 in 5 of the devices running either that OS or its free follow-up, Windows 8.1. Approximately 48 million machines ran Windows 8 in December 2015.

Since Windows 10's late-July debut, the combined Windows 8-Windows 8.1 user share has declined by about 18%, with the largest contraction credited to 8.1, which dropped by 21%. That makes sense: Owners of Windows 8.1 devices can upgrade directly to Windows 10, while Windows 8 users cannot.

To continue to receive support, Windows 8 users must either upgrade to Windows 8.1 -- which Microsoft will back until Jan. 10, 2023 -- or first upgrade to 8.1, then conduct a second upgrade from that to Windows 10. Consumers and businesses running Windows 8.1 Home or 8.1 Professional are eligible for the free Windows 10 upgrade, an offer set to expire in July.

Microsoft has published instructions for upgrading from Windows 8 to Windows 8.1 on its website.

This story, "Microsoft revokes Windows 8's patch privileges today" was originally published by Computerworld .