Rather than having one fermion field , it can be split up into separate components for each type of particle. This mirrors the historical evolution of quantum field theory, since the electron component (describing the electron and its antiparticle the positron) is then the original field of quantum electrodynamics, which was later accompanied by and fields for the muon and tauon respectively (and their antiparticles). Electroweak theory added formula_6, and formula_7 for the corresponding neutrinos, and the quarks add still further components. In order to be four-spinors like the electron and other lepton components, there must be one quark component for every combination of flavour and colour, bringing the total to 24 (3 for charged leptons, 3 for neutrinos, and 2·3·3 = 18 for quarks). Each of these is a four component bispinor, for a total of 96 complex-valued components for the fermion field.