A galaxy collision occurs when two or more galaxies come close enough to each other that their gravitational forces interact. This interaction can lead to the merging of galaxies, resulting in new structures and star formations. The process can take millions to billions of years and often creates spectacular cosmic events. During a galaxy collision, stars within the galaxies usually do not collide due to the vast distances between them. However, the gas and dust in the galaxies can interact, leading to bursts of star formation. Famous examples of galaxy collisions include the Milky Way and Andromeda galaxies, which are on a collision course.