There are two ways to define pageflow in Seam:
Using JSF or Seam navigation rules - the stateless navigation model
Using jPDL - the stateful navigation model
Very simple applications will only need the stateless navigation model. Very complex applications will use both models in different places. Each model has its strengths and weaknesses!
In practice, both navigation models have their place, and you'll quickly learn to recognize when to prefer one model over the other.