Composite particles are subatomic particles that are made of more than one quark. Simple particles like protons are actually composites of multiple quarks. Protons are known as baryons, which means that they are made of exactly three quarks. Baryons are in a family called Hadrons, which simply means that they are made of quarks. The only other subcategory of Hadrons is Mesons, which are made of one quark and one antiquark.