Group theory, in the chemistry sense, involves making use of the symmetry of a molecule to better understand its physical properties. By examining the symmetry properties of a molecule, it can be placed into a “point group” that describes the symmetry operations (rotations of reflections) that characterize the molecule’s symmetry. Group theory allows chemists to understand an impressive number of molecular properties including the spacing of energy levels of the orbitals in a molecule, the symmetry of the molecular orbitals, the types of transitions that can occur (like vibrational and electronic excitations), and what the delocalized vibrational motions of a molecule look like. It is very impressive that symmetry can tell us so much about molecules without the need for any complex calculations!