Composite particle

All observed subatomic composite particles are called hadrons. All bosonic hadrons are called mesons and all fermionic hadrons are baryons. The most well-known baryons are the constituents of atomic nuclei called protons and neutrons, and collectively named nucleons. The quark model of hadrons posits that mesons are built out of a quark and an antiquark, whereas a baryon is made up of three quarks.