An alert will appear on your PC screen indicating that the operating system will no longer receive security updates from January 10, 2023.
If you are still one of the users who use Windows 8.1 and you have performed the latest cumulative update (KB5015874), you will see a window appear on your machine announcing the end of life of the system in January 2023. More precisely, Microsoft will stop on January 10 to offer extended support, as well as technical support, for this version of the OS launched in October 2013.
Indeed, Windows versions have two types of support: mainstream support and extended support. Mainstream support includes new features, service packs, feature fixes, and security updates. It ended on January 9, 2018 for Windows 8.1. Extended Support is for security updates only and lasts for five years after Mainstream Support ends. This means that you will still be able to use Windows 8.1 after January 10, but it will no longer receive security updates, which makes it more vulnerable to possible hacker attacks.
Microsoft specifies that the display of the alert window does not concern the Pro, Enterprise and Embedded versions of Windows 8.1. When alerted, you can choose to be reminded later (after 35 days) or just after the end of extended support date.
The case of Windows 10 is a bit different, as the system has experienced new major releases over the years. Thus, the support for the 20H2 version has just ended on May 10 (for the Family and Pro editions). It will stop on December 13 for the 21H1 version and on June 13, 2023 for the 21H2 version. Enterprise and Education editions in use will have up to an additional year of breathing space, but Windows 10 is scheduled to end of life on October 14, 2025, for all editions.