The Standard Model groups two major extant theories — quantum electroweak and quantum chromodynamics — into an internally consistent theory describing the interactions between all experimentally observed particles. Standard Model describes each type of particle in terms of a mathematical field, via quantum field theory.

Standard Model is a theory of three of the four known fundamental interactions and the elementary particles that take part in these interactions. These particles make up all visible matter in the universe -leptons, mesons and baryons. The lightest are the leptons and the heaviest are the baryons. This was true until the discovering of lepton taon which is almoast two times heavier than the proton (which is baryon). The main difference between these particles istheir structure. It is considered that leptons are structureless and mesons and baryons are made from quarks.

Every particle has its antiparticle with has the same mass but opposite electric charge. For example, the antiparticle of electron is antielectron, or positron. Then particle and antiparticle meet they stop existing and are formed photons and other particles.

Some elementary perticles and their properties: