  Fragmentation functions of pion, kaon, and nucleon are determined by global
analyses of hadron-production data in $e^+e^-$ annihilation. It is particularly
important that uncertainties of the fragmentation functions are estimated for
the first time. We found that light-quark and gluon fragmentation functions
have large uncertainties, so that one should be careful in using these
functions for hadron-production processes in heavy-ion collisions and lepton
scattering. The analysis is extended to possible exotic hadron search by
fragmentation functions. We found that internal structure of $f_0 (980)$, such
as $s\bar s$ or tetraquark configuration, can be determined by noting
differences between favored and disfavored fragmentation functions.
