A positron is a subatomic particle that is the antimatter counterpart of an electron. While an electron has a negative charge, a positron carries a positive charge. Positrons are produced in certain types of radioactive decay, such as beta-plus decay, and can also be generated in high-energy processes, like those occurring in particle accelerators. When a positron encounters an electron, they can annihilate each other, resulting in the release of energy in the form of gamma rays. This annihilation process is utilized in medical imaging techniques, such as positron emission tomography (PET), which helps doctors visualize metabolic processes in the body.