We missed this one when it was first announced, but in case you're wondering, Microsoft has stated that it plans to support Windows 8.1 up until January 10, 2023. Mainstream support will cease a little sooner, expiring on January 9, 2018, after which time the "Extended Support" phase kicks in. What's the difference between Mainstream Support and Extended Support? Here's what you need to know.
Mainstream Support covers the following:
Paid support (per-incident, per hour, and others)
Security update support
Non-security hotfix support
No-charge incident support
Design changes and feature requests
Product-specific information that is available by using the online Microsoft Knowledge Base
Product-specific information that is available by using the Support site at Microsoft Help and Support to find answers to technical questions
Extended Support covers all of the same, minus the entries that have been bolded. There is an option to extend non-security hotfix support, though it requires an extended hotfix agreement, purchased within 90 days of Mainstream Support ending, Microsoft says.
The other interesting tidbit is that Microsoft is mandating an upgrade to Windows 8.1.
"Windows 8 customers will have two years to move to Windows 8.1 after the General Availability of the Windows 8.1 update to continue to remain supported under the Windows 8 lifecycle," Microsoft says.