Doctor Who has spawned three spin-off series' since its return in 2005. Doctor Who sits at the heart of the franchise, with The Sarah Jane Adventures, Class and Torchwood
catering for the children, teenager, and adult markets respectively.
The question is: how does it all fit together? Below is a chronology of
the show's main crossover episodes. It's by no means exhaustive, but
what follows should be enough to give the new viewer a rough idea of
what to expect, and the order in which to expect it.the franchise, with
