Everything is made up of atoms, but what are atoms made up of? The simulation explores subatomic particles. It focuses on hadron, boson, and lepton groupings as scholars learn about quarks, neutrinos, gluons, and more.

This site has a definition and properties of Leptons, the "Basic building blocks of matter." There are links to table of properties and more information.

This particle physics tutorial discusses the different types of leptons: the electron, tau lepton, muon lepton, and neutrinos.