Windows 10 will be a free upgrade for Windows 7 and 8.1 users for one year

Microsoft to make Windows 10 free to users running Windows 7, Windows 8.1 and Windows Phone 8.1 on their devices.

"Once a device is upgraded to Windows 10, we'll be keeping it current for the supported lifetime of the device," said Terry Myerson, executive vice president of the Operating Systems Group.

All customers running Windows 7, Windows 8.1 and Windows Phone 8.1 will be able to upgrade to Windows 10 for free within a one-year period following the operating system's launch later this year. Windows 10 is set to launch this Autumn.