摘要: Gauge theories are believed to belong the class of which describe nature. At each energy (distance) scale nature can be described in terms an effective gauge theory. For example at present available energies physics seem correctly by standard SUc (3) × SU(2) U(1) It is important note that degrees freedom considered elementary on a given may turn out composite higher scale. Given (effective) theory, its large distance properties (phase structure, symmetry realization etc.) determined structure vacuum. In these lectures I would like concentrate two aspects vacuum (without and with fermions).