  The field of fragmentation functions of light quarks and gluons is reviewed.
In addition to integrated fragmentation functions, attention is paid to the
dependence of fragmentation functions on transverse momenta and on polarization
degrees of freedom. Higher-twist and di-hadron fragmentation functions are
considered as well. Moreover, the review covers both theoretical and
experimental developments in single-inclusive hadron production in
electron-positron annihilation, deep-inelastic lepton-nucleon scattering, and
proton-proton collisions.
