Protons – Protons are subatomic particles that are found in all atoms and have an elementary charge of +1. Protons, like neutrons are nucleons and are cemented together by nuclear forces to form the atomic nucleus. The nucleus of the hydrogen atom consists of a single proton whereas its isotopes deuterium and tritium contain one and two neutrons respectively; in addition tritium is radioactive. The number of protons in the nucleus defines the element. The proton has a natural spin that produces a magnetic field similar to a bar magnet. Thus, if the proton is placed in an external magnetic field the proton will precess and the frequency of the precession forms the basis of nuclear magnetic spectroscopy (NMR). Protons are composed of three quarks (and are consequently baryons) comprising two up quarks and one down quark held together by gluons. 

Further Information on this Topic can be found in the books of R.P.W. Scott by following the listed links