Microsoft Ends Windows 8.1 Support Today, Here’s What That Means The end of support means the operating system will be vulnerable to security risks. Users should upgrade immediately.

10 years after it first launched, Windows 8.1 has reached the end of extended support. After today, the operating system will not receive security updates or technical support.

Valve's reasoning for dropping Windows 7, 8, and 8.1 is due to Steam relying on an embedded version of Google Chrome, which no longer functions on older versions of Windows.