The deadline this week comes 18 months after Microsoft warned that it would cease to support Internet Explorer 8, 9 and 10, giving users time to upgrade.
Microsoft suggests users upgrade to Internet Explorer 11 on Windows 7 and 8.1, or use the new Edge browser if they're on Windows 10. Edge is able to launch Internet Explorer 11 when needed, for backwards compatibility.
Edge and Internet Explorer 11 will be supported for the full life of Windows 7, 8.1 and 10, Microsoft said.
The company is also touting enterprise mode in Internet Explorer 11 as a workaround for companies and organisations with web applications that are only compatible with older IE browsers.
Should organisations and users not upgrade and continue to use older, unsupported versions of Internet Explorer, Microsoft warned, it would place them at risk of viruses and other malicious software that exploit security flaws and bugs in the browsers.
Using unsafe versions of Internet Explorer could also place organisations at risk of breaching some regulatory compliance requirements, Microsoft said
This article originally appeared at iTnews.com.au