Antiparticle

For most particle types (and every fermion type) there is another particle type that has exactly the same mass but the opposite value of all other charges (quantum numbers). This is called the antiparticle. For example, the antiparticle of an electron is a particle of positive electric charge called the positron. Most boson types also have antiparticles except for those that have zero value for all charges, such as a photon or a composite boson made from a quark and its corresponding antiquark. In these cases there is no distinction between the particle and the antiparticle; they are the same object.