The proton is a subatomic particle. It is each of the positively charged particles in the atom nucleus whose mass is almost the same as that of the neutrons.
Every element (there are 118 elements known and all are listed in the periodic table) has different number of protons, so it is the number of protons what differentiates the elements.
Other subatomic particles are the neutrons and the electrons. Other small particle that are related witht the quantum model of the matter is the photon.
Neutrons, electrons, and photon are non-examples of a proton.
If a particle has either negative charge or no charge, it is not a proton. Also, if the relative mass of the particle is not 1 (relative to the neutron) it is not a proton either.
