Earth's rotation and the gravitational pull of the sun and moon create tides on our planet. Because the sun is so much larger than the moon (27 million times more masssive), it has a much bigger graviational pull on Earth. The sun's extreme mass, and therefore gravitational pull, is why Earth (and the other planets and celestial bodies in the solar system) orbit the star. 

But tidal force's dependance on gravity can be a bit deceiving. Unlike gravity, tidal forces are much more dependant on distance than mass. So, the relatively small moon exerts a much stronger tidal force on Earth than the gargantuan sun because it is so much closer—on average the moon is 384,399.9 kilometers (238,855 miles) from Earth, while the sun is 149.6 million kilometers (92.92 million miles) away.

Earth's oceans, other bodies of water, and to a much lesser extent land respond to the moon by bulging and dipping as the moon revolves around Earth. The sun also plays a role in the formation of tides, but a much smaller one. Tides move around Earth as bulges in the ocean. As the ocean bulges toward the moon, a high tide is created. The high tide on the side of Earth facing the moon is called the high high tide. The high tide caused by the bulge on the opposite side of Earth is called the low high tide. (A low high tide may be understood as the moon's tidal force pulling the planet—not the ocean—toward it.)