Microsoft is finally retiring old versions of Internet Explorer (IE) this month. As of January 12, IE 8, 9, and 10 will kick the bucket, ceasing to receive updates or official support, thereby leaving you in the cold and vulnerable to viruses and such, but allowing developers to further focus on newer technology. IE 11 will still be on the menu for the foreseeable future, and then of course there's Edge.
If you are an old fogey determined to not upgrade or just don't even know how (if you're on this website, this probably isn't you, but hey), the company encourages you to do so to get the benefit of "improved security, increased performance, better backward compatibility, and support for the web standards that power today's websites and services." A final update for the aging browsers will nag you to do so, as well.