Having discussed bosons, it is only proper to devote some attention to this other CATEGORY OF ELEMENTARY PARTICLES. These particles are notable for their half-integer spin, obedience to the Pauli exclusion principle, and conserved quantum numbers. As opposed to bosons, this type of particle can be either elementary (such as the muon), or composite (like the proton). What is this CATEGORY OF PARTICLE, which includes baryons and leptons?
fermion