How does the moon affect Earth's oceans and tides?

The moon's gravitational pull is the primary driver of Earth's tides. As the moon orbits Earth, its gravity tugs on the oceans, creating a bulge of water on the side of Earth facing the moon. A corresponding bulge also forms on the opposite side due to inertial effects. As Earth rotates, different coastlines pass through these bulges, producing the high and low tides experienced roughly twice daily. The sun also contributes to tidal forces, and when the sun and moon align during new and full moons, their combined gravity creates stronger spring tides. When they are at right angles, weaker neap tides occur. The moon also slows Earth's rotation very gradually and stabilizes the planet's axial tilt over long timescales.