BONUS FACT: The sun also causes tides on the earth, but they're only about half as strong as the moon's. When the sun & moon line up during full & new moons, tides are extra big. MinutePhysics...
========== Because gravity gets weaker at longer distances, the moon pulls the near-side ocean more than the Earthand the Earth more than the far-side ocean.When the Earth spins relative to the moon, the water sloshes, and we call it the tides.