  The charm quark has unique properties that make it a very important probe of
many facets of the Standard Model. New experimental information on charm decays
is becoming available from dedicated experiments at charm factories, and
through charm physics programs at the b-factories and hadron machines. In
parallel, theorists are working on matrix element calculations based on
unquenched lattice QCD, that can be validated by experimental measurements and
affect our ultimate knowledge of the quark mixing parameters. Recent
predictions are compared with corresponding experimental data and good
agreement is found. Charm decays can also provide unique new physics
signatures; the status of present searches is reviewed. Finally, charm data
relevant for improving beauty decay measurements are presented.
