  The two $B$-factories, Belle and BaBar, has been played major roles in the B
decays study. Their wonderful design and excellent operation enables their
fruitful analysis results. Also recently the Tevatron experiments, CDF and DO,
join the game with their $B_S$ studies. From the experimental results of $B$
decay studies, we learn that most of measurements are consistent with the
Standard Model (SM). Some discrepancies from the SM has been found in the
measurements of the phases and magnitudes of CKM unitary triangle. There are
also various theoretical models that possibly give the contributions. These
will relay on further validation with new experimental results.
