(electron-like antimatter particle with electric charge of +1)
A positron is the antimatter-equivalent of an electron
(i.e., an antielectron),
with the same mass but opposite electrical charge.
It is a stable lepton that can be produced by pair production,
but unlike antiprotons and antineutrons, is also produced by
"normal-matter" nuclear reactions, such as fusion and
beta decay. The term beta particle refers to
either an electron or a positron produced by beta decay.
Like any particle/antiparticle pair, the meeting of a positron and
an electron results in annihilation, which produces two photons
with whose photon energies sum to the kinetic energy and
rest energy of the positron and electron, minimally
1.022 MeV. This is the inverse of pair production.