Radial chart depicting the subatomic particles quarks, leptons and bosons. Quarks (top half of outer ring) are tiny particles that aggregate to form larger ones. The letters denote the six types of quarks: up (u), charm (c), top (t), down (d), strange (s) and bottom (b). Leptons (bottom half of outer ring) do not undergo strong interactions. The types are (far left to right): tau, muon, electron, tau neutrino, muon neutrino and electron neutrino. The middle ring shows bosons, which are force carrying particles. They are (clockwise from top right): gluon, Z boson, W+/W- bosons and photon. At centre is the Higgs boson.