Protons are subatomic particles that are found in the nucleus of every atom of every element. They have a positive electrical charge and are composed of three valence quarks, two up quarks and one down quark, held together by the strong force. Protons are not elementary particles, but rather composite particles, and are classified as hadrons. They are slightly less massive than neutrons and 1,836 times the mass of an electron. The protons positive charge is equal and opposite to the negative charge on an electron, meaning a neutral atom has an equal number of protons and electrons. Protons are stable particles that have not been observed to break down.

In summary, protons are positively charged subatomic particles that are found in the nucleus of every atom and are composed of three valence quarks held together by the strong force.