Just because Internet Explorer sits on the sidelines in Windows 10 doesn't mean you're safe from IE-specific exploits. Microsoft has released a patch for a "critical" flaw in the browser that lets attackers remotely control just about any semi-recent version of Windows, ranging from Vista to 10, just by serving you a maliciously-coded web page. The likelihood of running into an exploit is slim if you prefer to use Edge or a third-party browser, but you'll probably want to get the fix regardless... just in case you feel nostalgic enough to click on that blue E.