Hadron physics is a subfield of particle and nuclear physics dedicated to the investigation of hadrons. It examines the properties, internal structure, and interactions of these composite particles, which are made of quarks and gluons bound by the strong nuclear force described by Quantum Chromodynamics (QCD). This field is fundamental to understanding the constituents and behavior of atomic nuclei, the nature of strongly interacting matter, and phenomena such as quark confinement and chiral symmetry breaking.