Galaxy classification is a system used by astronomers to categorize galaxies based on their shapes and structures. The main types include spiral galaxies, which have a flat, rotating disk with arms, elliptical galaxies, which are more rounded and lack distinct features, and irregular galaxies, which do not fit into the other categories due to their chaotic shapes. This classification helps scientists understand the formation and evolution of galaxies. Each type can vary in size, brightness, and star formation activity, providing insights into the universe's history. The Hubble Space Telescope has played a significant role in observing and classifying these celestial objects.