The study of the stellar content and physics of the ionized gas in local high-mass star-forming regions is specially important for better understanding extragalactic starbursts. Recent observations from space telescopes and near-infrared detectors have provided a wealth of new information about the gas and stars in these objects. In this paper, I review some relevant observational results related to: a) the stellar content in high and low-mass stars of the ionizing clusters; b) the interplay between the gas and stars; c) the role of ionization fronts; d) the chemical composition of the ionized gas.