In physics, a hadron is a subatomic particle composed of quarks and gluons.
The class of hadrons is further subdivided into three subclasses.
- Baryons, formed by three quarks, like protons and neutrons
- 'Exotic Baryons', including the pentaquark, a particle of five quarks
- Mesons, formed by configurations quark/antiquark pairs, such as pions and kaons.