On January 12, 2016, Microsoft is officially dropping support for all but the latest version of Internet Explorer. For a surprisingly high number of laggards, it's time to upgrade or face a world of hurt. So what's holding them back? By Ed Bott for The Ed Bott Report | December 11, 2015 -- 01:13 GMT (17:13 PST) Next month, Microsoft will officially stop delivering updates for all but the latest Internet Explorer version on each Windows version it supports. Although the company provided almost two years' warning, the population still using older versions of Internet Explorer appears to be uncomfortably high. How many people are using Microsoft browsers (Internet Explorer and Microsoft Edge) on desktop PCs, laptops, and Windows-powered hybrids? And what percentage of those customers are going to stop getting security updates after January? Getting answers to those questions turned out to be harder than I thought. In fact, the three most commonly cited sources of information on usage share for browsers and operating systems publish authoritative-looking numbers that are almost comically far apart. Instead of picking one, I'll give you the numbers from all three sources and maybe together we can make some sense of things. First, how many people and PCs use Microsoft browsers? I looked at worldwide desktop browser share by version for the three-month period from September through November 2015. Here's the result: The number on the left counts the percentage share for Microsoft desktop browsers (all versions of Internet Explorer as well as the new Microsoft Edge browser, available only in Windows 10). StatCounter, which measures pageviews rather than trying to count individual devices, says Microsoft browsers account for just over 18 percent of all worldwide web traffic from desktop PCs and laptops. Google is the absolute leader in StatCounter's numbers, with an average of 57 percent of all worldwide pageviews from desktop browsers during the survey period. The U.S. Digital Analytics Program, which counts visits to U.S. Government websites from individual devices, helpfully breaks out the desktop and mobile percentages. Those numbers say Microsoft browsers accounted for 35.8 percent of the 1 billion or so visits from desktop devices in that three-month period. The remainder is divided between Chrome, Safari, Firefox, Opera, and a small number of obscure browsers. And then there's Net Market Share, which makes geographic adjustments to its raw numbers and also subtracts pages that are loaded but typically never seen. For the period in question, the Net Market Share numbers say Microsoft browsers account for 50.7 percent of all worldwide visits from devices running a desktop operating system such as Windows or OS X. Unhelpfully, those numbers suggest that Microsoft browsers are used regularly on at least 200 million and possibly as many as 800 million Windows PCs. Oh dear. That doesn't narrow things down much at all, does it? The more interesting question is this follow-up: Among the population that chooses to use Microsoft browsers, which versions are they using? Here's the result: Depending on whose numbers you look at the share of people using a Microsoft browser who are on the latest version (Internet Explorer 11 on Windows 7 or later, with Edge as an option on Windows 10) is well over 50 percent and possibly as high as two-thirds. I was surprised to see Microsoft Edge getting so much real-world usage only four months after its release, getting between 6.3 and 6.6 percent share, or about 1 in every 4 Windows 10 machines, as measured by StatCounter and confirmed by the DAP numbers. (Net Market Share's numbers are down across all versions except Internet Explorer 8, which is unnaturally high. Take the differences with a healthy serving of salt.) So, who are those laggards still on earlier versions? Let's break it down group by group. Internet Explorer 10 - All three data sources find a rare point of agreement here, with this version accounting for 9.2-9.3 percent of usage. This release runs on only two desktop Windows versions. On Windows 7, the upgrade to Internet Explorer 11 is easy. On Windows 8, where it's the default, the only way to get a supported Microsoft browser is to upgrade the operating system to 8.1 or 10. Either way, anyone in this group should feel pressure to upgrade as soon as possible. Internet Explorer 9 - Believe it or not, there are people who are perfectly happy to be running Windows Vista today. Some small but not trivial number of devices (roughly 2 percent of all Windows PCs) are running Vista. For those diehards, this is the last supported version of Internet Explorer, and it will continue to get security updates for another year. The larger problem is Vista itself, which will no longer be supported come April 11, 2017. Internet Explorer 8 - Here's another place where three different metrics give three wildly different results. Somewhere between 5.8 and 23.5 percent of web traffic from Microsoft browsers is from this version. This version was the last one to run on Windows XP, so that likely accounts for the lions share of this number. There are also corporate sites running Windows 7 that standardized on Internet Explorer 8 for compatibility with line-of-business apps. If there's an IT pro in the house, these people desperately need to set up Enterprise Mode for Internet Explorer 11, which was built for precisely this purpose. Internet Explorer 7 and earlier - Anyone running one of these versions of Internet Explorer in 2015 has a real IT management problem, frankly. But if the underlying operating system is Windows 7, it's not too late to move to Internet Explorer 11 (and if necessary, turn on Enterprise Mode). So, come next month, more than 25 percent of all Internet Explorer users are going to get the very last security updates for their browser. That number will shrink as Vista machines retire and Windows 8 PCs get upgraded. But businesses that don't move off of their unsupported Internet Explorer version in 2016 could face a world of hurt. Until Edge gets support for extensions (with ad blockers and password managers at the top of the list), it isn't a contender for anything more than occasional slumming among heavy browser users. That support is due sometime next year, and could be a key selling point in Microsoft's campaign to have Windows 10 on a billion devices in the next few years.