Tides are the up and down movement of the oceans across land. Two of our sky's most dominate features, the sun and moon, control the timing and strength of tides. Although the moon is much smaller than the sun, its closeness to the earth results in about twice as much pull force. That is why we primarily say the moon affects our tides. Spring and neap tides demonstrate the pulling power of these two heavenly objects on our oceans.
The moon's gravity pulls the ocean's waters toward the part of the earth it is facing. On the opposite side it is pulling the earth away from the waters. This pulling causes the waters to bulge at these two points. The result is a high tide at the two bulging points and a low tide at the other two points because the water is being redirected. Each location on the earth passes through these points twice a day, usually experiencing two high and low tides daily.
Spring tides are the result of the moon and sun working together to exert more pull on the earth's oceans. When the moon is in its full and new stages the earth, sun and moon are all aligned. This extra gravity pulling on the same point of the earth causes stronger high and low tides. These tides are named spring tides not because of the season but because the tides are springing stronger up and down.
Neap tides are the result of the moon and sun working against each other's pull. When the moon is in its first and third quarter phases the earth, sun and moon are at a right angle to each other. Though the moon's pull is stronger, the sun's gravitational pull is lessening the effect of the moon's gravitational pull on the oceans. This means that twice a month we experience smaller high and low tides than normal.
During the moon's new phase it is on the same side of the earth as the sun. Normally, the difference between this spring tide and the one at the full moon when the earth is between the sun and moon is negligible. However, when the moon comes closest to the earth called its proxigee and it coincides with a new moon this extra pull of gravity results in an extreme high tide called the Proxigean Spring Tide.