In this article Tactical Theory: Vertical Build-Up Passing the author used the words advanced area for many times, for example
Every team utilises different build-up patterns in order to move into more advanced areas of the pitch
or
But midfielders, who have more license to move into advanced areas, can combine passing accuracy & aim with runs of their own.
Could you please explain for me what is an advanced area? I wonder is there an official definition of advanced area or it is just the dangerous area in opponent's field?