It has been a couple of years since Microsoft gave its users a chance to upgrade to Windows 10 for free. This was a very generous offer from the makers of Windows which, in turn, helped with the popularity of Windows 10. The offer had actually ended in June of 2016, but if you knew a few ways around, the upgrade was still possible. However, Microsoft is completely shutting down the free campaign on 31st December 2017.Right now, a copy of Windows 10 will run you about $119.99. And this is quite an expensive amount to pay for. So, if you haven't upgraded already, now would be a really good time. But then again, if someone hasn't taken an advantage of this free offer for over two years, they probably don't care at all.If you want to upgrade to Windows 10, you can do it with the help of Microsoft Assistive Technology, here is a link to that. The aforementioned link also mentions that this offer expires on the 31st of December 2017. So it's safe to assume that any method to get Windows 10 without paying is ending, unless if you crack your copy for activation, of course.Windows is a popular platform with a market share of 37.43%, only second to Android with 38.49% share. If we look more closely, even with the free upgrade scheme and everything, Windows 7 still leads with a 42.67% of the market share with Windows 10 following closely with a 40.95%. The closest to these two is Windows 8.1 with a 9.03% of the total windows share. (Source)