Facebook recently announced that it will stop supporting Internet Explorer 6 on its chat function with its next upgrade, planned for Sept. 15. With this move Facebook joins the German government and all the major security systems vendors in urging consumers and businesses to upgrade to IE 8 or to an alternative Web browser such as Mozilla Firefox or Apple Safari.

So what is wrong with IE6? First it is just old and outdated. Microsoft moved on years ago, and IE6 lacks many great features that are now standard. Users of more modern systems look on IE6 as a dinosaur in terms of functionality. Facebook’s stated reason for dropping IE6 is that it lacks advanced features of all modern Web browsers that are required for some of the new functionality it wants to add to its Chat app.

More important, however, are the security issues in IE6. One reason that Microsoft rewrote IE was that IE6 code has major vulnerabilities that are exploited by a list of nasty viruses. Having IE6 on your computer makes it a target for a lot of malware that is very hard to remove once it is there but that cannot attack IE8, Firefox, Google Chrome, or Apple Safari. And because a Web browser’s function is to reach outside your firewalls to access data and code on the Internet, it opens the door for this malware to invade not just one computer but any computer on your internal network with IE6 on it. If you are at all concerned about cyber-crime, then the first thing you should do is eliminate IE6 from your computer systems.

So why is IE6 still around, years after Microsoft has ceased selling it? There are three reasons. First, in its day it was ubiquitous. When IE6 was new, close to 90% of all desktop systems ran IE. That was the high point of Microsoft’s dominance of the Web browser market. Because of that, all Web sites at that time and for many years thereafter worked with IE6. Even today most do. That gives a great many users, who never upgrade their software, little reason to move to IE8.

Second, many consumers stay on their old computers until the computer dies – usually when the hard drive wears out. And many of these never upgrade their software – many believe it is too complicated for them to manage. So a lot of old computers that came with IE6 are still clunking away in homes. And others who perhaps switched to Firefox years ago may not realize they even have IE6 still. As long as it is there some applications may be using it occasionally just because they came set to use IE.

Third, in the business world many companies built IE6 into their corporate desktop image – the set of standard software they put on all computers in their offices. They have been reluctant to upgrade to a newer version because despite its serious security flaws IE6 is “good enough”, and they fear that newer versions of IE or other browsers might either conflict with other applications or not work with highly customized or custom-written applications that use it for Internet access.

Certainly, given the security problems alone, your company should do all it can to eliminate IE6 from all systems and software. However, the reality is that many individuals and organizations will not make that effort until they have an immediate reason. Perhaps this announcement from Facebook will give some that reason, and if more Web sites stop supporting IE6 that will increase pressure to finally ditch this dog.