A galactic merger occurs when two or more galaxies collide and combine due to their gravitational attraction. This process can take millions to billions of years and often results in the formation of a larger galaxy. During the merger, stars within the galaxies may not collide directly, but their gravitational interactions can lead to new star formation and the rearrangement of existing stars. These mergers can significantly alter the structure and dynamics of the involved galaxies. For example, when the Milky Way merges with the Andromeda Galaxy, expected in about 4.5 billion years, it will create a new galaxy with a different shape and star distribution. Such events are common in the universe and play a crucial role in galaxy evolution.