A large group of stars is called a galaxy. Galaxies are vast systems consisting of billions, potentially trillions, of stars, along with gas, dust, and dark matter, all bound together by gravity.
Our own galaxy, the Milky Way, is just one of the billions of galaxies in the universe. Each galaxy can vary significantly in size, shape, and structure. For instance, some galaxies are spiral-shaped, like the Milky Way, while others may be elliptical or irregular in form. The study of galaxies helps astronomers understand the formation and evolution of the universe.