> > > What happened to Windows 9?
> >
> > Apple has OSX version 10.something, so unless Windows is also on version
> > 10, it must be lagging behind, mustn't it ?
> >
> > Don't laugh, it's how marketing people think (and maybe also some
> > consumers....)
>
> I know it happens, but OS X 10.0 can out in 2001!

No, that's a tautology. The X in OS X is the roman numeral 10, which refers to the first 10 in version 10.0.
So it's OS X.0 that came out in 2001, and OS X.10 that's due now.

More info can be found at http://en.wikipedia.org/wiki/Software_versioning.

But the marketing version numbering is seriously off-kilter relative to the 'behind-the-screens' version:

Windows 3.1 = version 3.10
Windows 95 = version 4.00
Windows 98 = version 4.10
Windows 2000 = 5.0
Windows XP = 5.1
Windows XP 64-Bit Edition = 5.2
Windows Server 2003 = 5.2
Windows Server 2003 R2 = 5.2
Windows Vista = 6.0
Windows Server 2008 = 6.0
Windows Server 2008 R2 = 6.1
Windows 7 = 6.1
Windows Server 2012 = 6.2
Windows 8 = 6.2
Windows Server 2012 R2 = 6.3*
Windows 8.1 = 6.3*

(Source)

Windows 10 will probably be 6.4.

The entire list can be found at
http://en.wikipedia.org/wiki/List_of_Microsoft_Windows_versions


It's still nothing compared to Chrome: I don't know if Chrome OS follows the same version numbering scheme as the Chrome browser, because that's already at version 38...