"Regular security updates help protect computers from malicious attacks, so upgrading and staying current is important," Microsoft says on a web page about the change. Internet Explorer 11 offers "improved security, increased performance, better backward compatibility" and support for modern web standards, it added.
There are a few exceptions: For example, Microsoft will continue to provide support for Internet Explorer 9 on its older Windows Vista after the deadline because it's the latest compatible version for that operating system. But for the most part, users of old browsers will be on their own.
This change shouldn't be a surprise: Microsoft first announced the cutoff was coming back in August 2014.
Still, the shift will have a major impact on Internet users: By some estimates that means hundreds of millions of users will need to upgrade or be left at greater digital risk.
Microsoft is offering help for enterprise customers -- organizations with more than 500 employees -- looking to upgrade browsers before the cutoff. And that might be needed in some cases: Big companies and governments can be slow to move to the latest software because making those changes can be complicated to roll out across their organizations.
But most everyday users still running versions Internet Explorer 8, 9, and 10 can expect to get a final "End-of-Life" software update on the 12th that will include a prompt to upgrade their browser.