  Group theory is used in many textbooks of contemporary physics. However,
electromagnetic community often considers group theory as an "exotic" tool.
Graduate and postgraduate textbooks on electromagnetics and electrodynamics
usually do not contain a description of properties of electromagnetic fields
and waves on the basis of group theory. We discuss in this paper from the
didactic point of view, several types of symmetry and the corresponding groups
and representations. The benefits of the use of group theoretical methods are a
more deep physical understanding of the electromagnetic phenomena and a
significant reduction of numerical calculations. These methods are general and
exact.
