ABSTRACT
The focus of this entry is on information about the characteristics of “normal” stars primarily gleaned through the study of the optical light they emit. There is no doubt that significant advances in our understanding of some stars, e.g., compact stellar endpoints in binary systems, extremely hot and luminous stars, and young stars newly formed from the interstellar medium, have come through investigations of radiation they produce in the x-ray, ultraviolet, and radio portions of the electromagnetic spectrum. However, for the vast majority of stars in the galaxy that emit predominantly in the visible regimes constitute “the icing on the cake” as opposed to the substance of the basic layers.
