The Doctor is Out

[glatt]

I've watched an episode or two of Doctor Who back when that guy wore the long scarves, but don't follow it at all.

When people number the Doctors, like they talk about the 9th Doctor, or whatever, are they talking about the storyline? Or is is just because it's such a long series and they keep getting new actors? In other words, does the plot make any reference to the fact that there have been numerous Doctors?

In the TV show Bewitched, there were two actors that payed the husband Darren. They switched actors after a few years. But there was only one Darren.