Hadrons
Hadrons are composite particles that contain quarks and/or antiquarks, bound together by gluons. Those made up of three quarks, each of a different colour, are called baryons. The nucleus components, protons and neutrons, are baryons. Those formed by a quark of a given colour and an antiquark of the associated anticolour are called mesons.Other hadrons of different compositions, called exotic hadrons, have been recently discovered: tetraquarks and pentaquarks.