Microsoft ended support for Windows 8 on Wednesday, January 13, which means the three-year-old operating system will no longer receive the necessary security updates to keep hackers at bay, International Business Times reports.

This leaves more than 40 million users with the only option to upgrade to a later version of Windows to remain supported.

Microsoft still supports Windows 7 and Windows Vista, which surprises several users about the end of support for Windows 8. Technically, Windows 8 users must be supported till 2022, as per Microsoft's 10-year support policy. But a quirk in the support life cycle changes that and requires Windows 8 users to upgrade immediately.

In simple words, Microsoft branding for the OS is to be blamed. According to Microsoft's support document, "Windows 8.1 falls under the same life cycle policy as Windows 8, and will reach end of Mainstream Support on January 9, 2018, and end of Extended Support on January 10, 2023. With the General Availability of Windows 8.1, customers on Windows 8 have 2 years, until January 12, 2016, to move to Windows 8.1 in order to remain supported."

Microsoft offers another OS version "Windows 8.1 Update," which is basically an upgraded version of Windows 8.1.

Microsoft hasn't been able to draw distinct lines between the different versions of Windows 8 released over the past few years.

Users upgrading to Windows 8.1 Update will be supported till 2023, according to Microsoft's lifecycle page.

The only safe option for Windows 8 users is to upgrade to a supported OS. With the end of support, your Windows 8 PC will not seize to work but it simply won't receive any future security patches that keep users protected, IBTimes says.

In all fairness, Windows 10 is the company's latest OS and is supported till 2025. So if you do not wish to be worried about end of life support, your options are clear. Windows 7 will be supported till 2020 and Windows 8.1 Update will be supported till 2023.