A positron is another name for an antielectron. It is the antimatter particle of the electron. It is like an electron but positively charged.

An antihydrogen atom is made up of a positron (the antiparticle of the electron) and an antiproton (the antiparticle of the proton). Over the past 20 years, physicists at CERN have perfected the art of creating and storing actual atoms of antimatter, enabling them to study it at a whole new level. In 2016 they have shown that the laws of physics are identical for antihydrogen and hydrogen. Read 'Laser excites antimatter atoms for first time' to learn how physicists verified identical laws of physics at work with antihydrogen.