The
crown prince is the
prince who is next in line to
ascend to the
throne. These days, nearly all
monarchies and
empires follow
primogeniture,
i.e. naming the
firstborn (oldest) son as the crown prince. Before the advent of this system, the death of the
regent often resulted in
civil war between various
contenders to the throne.
Crown prince differs from heir apparent solely in that
a crown prince is always male, while a heir apparent may also be female (eg. a crown princess).