The Standard Model divides quarks and leptons into three groups, so called families. The table to the left gives an overview showing the labels and electrical charges, in units of the electron charge e, of the matter particles. Note that quarks have charges in fractions of e, while the three charged leptons have the same charge as the electron (-e, or shorter, -1)

All matter we see in our surroundings is built up of u and d-quarks and of electrons. These three belong to the first family. All three families were important in the very early universe, but since then the particles in the second and third family have decayed into particles of the first family.