I know very little about computers and I was told that if the upgrade message was in the centre of the screen it was not genuine. Therefore, when I got it I just switched my computer off and, so far, it has stayed with Windows 7 and is working OK.
Today, my wife was playing some game on hers using Windows 8 and, in the middle of a game, the upgrade window came up and she switched off the computer. When she switches it on again, it just continues the upgrade to Windows 10.
My question is, how does one know if this is a genuine upgrade? If it isn't genuine, what pitfalls does it contain for the unwary?