>> a method of
>> "dual booting" Windows and Mac OS. Meaning, that either one or the
>> other
>> would be running at any given point of time.
>
> The impression I was under was that both OSes were active and you just
> flipped between the two with a sort of super alt-tab command.
In the case of Bootcamp, only one OS is in operation at the same time
(there are other solutions, Parallels is one, that run simultaneously,
but they are not as fast).
However, each OS, while it is running has access to the other's file
system, though these file systems are different to some extent (which
is configurable).