Galaxy sizes is a research area in astronomy that focuses on the study of the sizes of galaxies found in the universe. Galaxies vary greatly in size, ranging from small dwarf galaxies containing only a few billion stars to massive galaxies containing hundreds of billions of stars. Researchers study galaxy sizes to better understand the formation and evolution of galaxies, as well as the distribution of matter in the universe. By measuring the sizes of galaxies and comparing them to other properties, such as their mass, shape, and composition, scientists can gain insights into the processes that govern the growth and development of these cosmic structures.