Why do stars appear to move across the sky?

Stars appear to move across the sky due to the rotation of the Earth in its orbit. As the Earth rotates the view of what can be seen changes along with the planets' positioning in the solar system. The location of a person on the planet and the tilt of the planet both affect what stars can be seen in the night sky and when they can be seen.

Stars stay in the same patterns as they move across Earth's night sky. This, over the centuries, has given rise to groups of stars being named as constellations, because they created shapes or helped travelers find their way long before the world had things like GPS systems or maps on phones, as the stars themselves do not change positions.