A spiral galaxy is a type of galaxy characterized by its distinct spiral arms that wind outward from a central bulge. These arms are made up of stars, gas, and dust, and they often contain regions of active star formation. The Milky Way is an example of a spiral galaxy, showcasing a beautiful structure that can be observed from Earth. Spiral galaxies are classified into different categories based on their appearance, including Sa, Sb, and Sc, which indicate the tightness of the spiral arms and the size of the central bulge. They are among the most common types of galaxies in the universe, contributing to the vast diversity of cosmic structures.