Terry Myerson, Windows and Devices Group executive vice president, confirmed in a blogpost dated 29 October that all devices running on Windows 7 and 8 will be automatically updated to Windows 10 in the months to come.
The process will be quite small with just two steps involved. At first, Microsoft will change the update to "Optional",and then in early 2016, it will change it to "Recommended", which means every user with "automatic updates" enabled on their device will have Windows 10 automatically downloaded without asking for any permission.
The upgrade will be automatic. Myerson explained that "after any upgrade, you can easily go back to your prior version of Windows within 31 days if you choose."
Microsoft has claimed that 110 million devices are already running on Windows 10, just two months after its release.