The discovery of the neutron, in the early quarter of the 20th century,
signaled the existence of a new force, binding the constituents of the nuclei,
which was called the strong force. Much have we learned since then. Baryons
and mesons were discovered. Quarks and gluons were seen to be the elementary
strongly interacting particles. Color and flavor turned out to be its
symmetries. Asymptotic freedom, spontaneous chiral symmetry breaking and
confinement define its dynamics. We believe we can write down the mathematical
expression for its theory, Quantum Chromodynamics (QCD), but no one has ever
found its full solution. Experiments are being developed where we hope to
find inspiration for understanding all the properties of QCD.