EXA2011

Belle experiment at the KEKB factory, originally dedicated to studies of $B$ mesons, was proved to be a great place also for studying charm physics. The QCD motivated measurements of spectroscopy, decays and production of charmed and charmonium states were succesfully performed at Belle and initiated a lot of theoretical work. In particular, recent discoveries of charmonium-like resonances indicate a renaissance of the $c\overline{c}$ spectroscopy. These so called $XYZ$ states do not fit the conventional $c\overline{c}$ spectrum described, so far successfully, by the quark models. This suggests that some of them might be exotic and could realize an unproved area of QCD predictions.