Proton
The proton is a subatomic particle with an electric charge of +1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons.
The proton is also stable by itself. Free protons are emitted in some rare types of radioactive decay, but they soon pick up an electron and become neutral hydrogen, which then soon combines with other atoms. Free protons may exist in plasmas or in cosmic rays in vacuum.