If you or your company is still using Internet Explorer 10 or older versions of IE, then it is important that you move to IE11 (at a minimum) before January 12 2016. Microsoft will officially end support for browser products older than Internet Explorer 11. Many businesses are using older versions of IE to provide compatibility with older line-of-business and internal web applications. If you are not updating those apps to work on a newer more secure browser platform then you ought to start now in order to remove the serious security issues that this choice creates for your company. Those of you who are still on Windows Vista systems (why?) will be impacted too since that is the most recent browser that Vista supports.
Up-to-date versions of Google’s Chrome browser or Mozilla’s Firefox may be good replacements if they will work with your legacy web apps. Worth a try to see if they will work for you, before you make the final upgrade to Internet Explorer 11.