Spiral galaxies are a type of galaxy characterized by a spiral-like pattern in their structure. These galaxies typically have a central bulge surrounded by spiral arms that extend outwards from the nucleus. The spiral arms are regions of star formation, containing young, hot stars and interstellar gas and dust. Spiral galaxies are classified into two main types, based on the presence or absence of a central bar structure: barred spiral galaxies and unbarred spiral galaxies. Studying spiral galaxies can provide insights into the formation and evolution of galaxies, as well as the dynamics of stars and gas within these systems.