This lecture explores the various formation modes of galaxies, debunking the misconception that elliptical galaxies evolve into spiral galaxies. It delves into the role of collisions between galaxies, the influence of dark matter, and kinetic properties on galaxy formation. The simulation presented demonstrates the collapse of matter, the formation of structures like spiral galaxies, and their eventual destruction in galaxy clusters. It also showcases extreme cases of galaxy interactions resulting in the transformation of spiral galaxies into compact elliptical galaxies.