Star Formation Regions in Discs of Galaxies

Observational properties of unresolved into individual stars star formation regions in the optical range are considered. The results of the study of the physical parameters of the stellar population (size, mass, age) and the chemical composition of gas in star formation regions are presented. Key aspects of the technique used to estimate the physical parameters and different relations between observational and physical parameters of the young stellar population in star formation regions are discussed. The issues of the hierarchy of star formation regions and their regular distribution along the spiral arms and rings of galaxies are studied.