At the Build 2015 developer conference currently underway, Terry Myerson, executive vice president for Microsoft's operating system, mentioned a very big goal for the company:
"In two to three years" Windows 10 will be on 1,000,000,000 (billion) devices." 
This promise went straight to developers, to consider investing in Microsoft's upcoming operating system. The benefits of a huge database of Windows users offer huge financial incentives to developers.
Myerson, speaking at Build 2015, said that current estimates on Google Play suggest that Android KitKat is being used on “500 million devices.” He also added that the latest version of iOS 8 is being used far less than Android.
In that vein, Myerson also announced that charges are coming through your phone provider.
What does this mean? Users of all Windows devices will be able to make purchases without a credit card. The Windows Store bill will be delivered to them with their phone bill.
Microsoft says that carrier billing support will only be available for smartphones for now, but will soon be available for PCs and tablets.
