How leptons and quarks got mass and began to actively interact
The Higgs boson is responsible for the masses of quarks, leptons and intermediate bosons involved in weak interactions of elementary particles — it was specifically introduced into the theory in order to provide these particles with masses. The matter is that the masses of the particles can not be present in a theoretical model like other fundamental constants do, as that would violate the basic principles of its construction. Should the Higgs boson not exist, that would mean that nature has chosen not the easiest way to organize weak interactions of particles. A detailed study of the properties of the Higgs boson, the measurement of its mass and lifetime will respond to the question of how accurate is the Standard Model of electroweak interactions.