There wasn't Windows 9 actually. They went from Windows 8/8.1 to Windows 10.
They mostly did it to signify how big of a change it was from previous versions of WIndows, as well as to "distance" themselves from Windows 8 because of the backlash it got from the public (however I use it and like Win8...many others will disagree).
They mostly did it to signify how big of a change it was from previous versions of WIndows, as well as to "distance" themselves from Windows 8 because of the backlash it got from the public (however I use it and like Win8...many others will disagree).