What causes ocean tides to rise and fall daily?

Ocean tides are primarily caused by the gravitational pull of the Moon, with a secondary contribution from the Sun. The Moon's gravity pulls on Earth's 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 and the Moon orbit their common center of mass. As Earth rotates on its axis, different locations pass through these bulges, experiencing high tides roughly twice a day. The Sun's gravity also influences tides, though less strongly than the Moon's. When the Sun and Moon align during new and full moons, their combined pull creates stronger spring tides. When they are at right angles, weaker neap tides result.