  To address fermion mass hierarchy and flavor mixings in the quark and lepton
sectors, a minimal flavor structure without any redundant parameters beyond
phenomenological observables is proposed via decomposition of the Standard
Model Yukawa mass matrix into a bi-unitary form. After reviewing the roles and
parameterization of the factorized matrix ${\bf M}_0^f$ and ${\bf F}_L^f$ in
fermion masses and mixings, we generalize the mechanism to up- and down-type
fermions to unify them into a universal quark/lepton Yukawa interaction. In the
same way, a unified form of the description of the quark and lepton Yukawa
interactions is also proposed, which shows a similar picture as the unification
of gauge interactions.
