Galactic collisions occur when two galaxies come close enough to each other that their gravitational forces interact. This can lead to the merging of the galaxies over millions of years. During this process, stars within the galaxies may not collide directly due to the vast distances between them, but their gas and dust can interact, leading to new star formation. These collisions can significantly alter the structure and appearance of the galaxies involved. For example, when the Milky Way collides with the Andromeda Galaxy in about 4.5 billion years, it will create a new galaxy, often referred to as Milkomeda. Such events are common in the universe and play a crucial role in galactic evolution.