Microsoft is ending support for Windows 8 and older versions of Internet Explorer today.

Windows 8 users who haven't upgraded to Windows 8.1 and Internet Explorer users who aren't running the latest version of the web browser — IE 11, in most cases — will no longer have access to patches and updates to keep their software secure from malware and hackers when new vulnerabilities are discovered.

While Windows 8 was released in 2012, and Microsoft typically supports an operating system for a minimum of 10 years after its release, Windows 8 has been considered a "prior service pack" ever since Windows 8.1 was released in 2013. Prior service packs are only supported for 24 months once a new service pack is released.

"Unlike service packs that are typically just a collection of fixes, Windows 8.1 has new features and enhancements," Microsoft says.

Windows 8 initially received a lukewarm reception from users, who were confused about the tile-based interface and disappearance of familiar features such as the "start button." Microsoft brought the start button back and made it possible to boot up in "desktop mode" in Windows 8.1.

Users can download the upgrade from the online Windows Store.

Once Windows 8.1 has been installed, users also have the option of upgrading for free to Windows 10, released in July.

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When it comes to Internet Explorer, users of Windows 7, Windows 8.1 and Windows 10 will have to upgrade to IE 11, as they'll no longer get support for IE 8, 9, or 10. (Robert Galbraith/Reuters)

When it comes to Internet Explorer, users of Windows 7, Windows 8.1 and Windows 10 will have to upgrade to IE 11, as they'll no longer get support for IE 8, 9, or 10. IE 9 and 10 will still be supported on some operating systems that don't support IE 11, such as Windows Vista SP2.

Microsoft says IE 11 will be the last version of Internet Explorer. Windows 10 comes with a new browser called Microsoft Edge. However, Internet Explorer may still be needed for some older websites, such as those with ActiveX controls.