In particle physics, a hadron (from the, hadrós, "stout, thick") is a particle made of quarks held together by the strong force (similar to how molecules are held together by the electromagnetic force). Hadrons are either mesons (made of one quark and one antiquark) or baryons (made of three quarks). Other combinations, such as tetraquarks (an "exotic" meson) and pentaquarks (an "exotic" baryon), may be possible but no evidence conclusively suggests their existence . The best known mesons a… (More on Hadrons)