Tides are created because the Earth and the moon are attracted to each other, just like magnets attract each other. The moon tries to pull at anything on the Earth to bring it closer. But the Earth is able to hold onto everything except the water. Since the water is always moving, the Earth cannot hold onto it, and the moon is able to pull at it. Each day, there are two high tides and two low tides. The ocean is constantly moving from high tide to low tide, and then back to high tide. There is about 12 hours and 25 minutes between the two high tides. The interval between low and high tide is usually a little over 6 hours.
When the sun and moon are aligned, there are exceptionally strong gravitational forces, causing very high and very low tides which are called spring tides, though they have nothing to do with the season. When the sun and moon are not aligned, the gravitational forces cancel each other out, and the tides are not as dramatically high and low. These are called neap tides. Spring tides occur during the full moon and the new moon. Neap tides occur during quarter moons.