The document discusses different types of galaxies: - Spiral galaxies have a central bulge and spiral arms where most star formation occurs. They make up about 60% of galaxies. The Milky Way is a spiral galaxy. - Elliptical galaxies have older, low mass stars and make up 10-15% of galaxies. They are found near the centers of galaxy clusters. - Lenticular galaxies are disk-shaped like spiral galaxies but have lost most of their gas and dust, resulting in little star formation. They can be mistaken for elliptical galaxies due to their faint spiral arms.