Galaxy mergers occur 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 a merger, the stars, gas, and dust from the galaxies interact, leading to new star formation and changes in the galaxies' structures. These events are common in the universe, especially among smaller galaxies. For example, the Milky Way is on a collision course with the Andromeda Galaxy, which is expected to merge in about 4.5 billion years. Such mergers play a crucial role in the evolution of galaxies.