Tide

This article is about the oceanographic event. For the laundry detergent, see Tide (soap).

A tide occurs when a body of water recedes or advances from its previous level to a higher or lower level, respectively. This change in water level is dependant upon several factors: wind currents, gravitational shift, and change in flow direction from greater to lesser bodies of water. The water line is indicitive of the current tide condition, either high or low.

Earth's moon plays a major role in the occurrence of oceanic tides. As the moon rotates around the Earth, a gravitational pull occurs in the surfaces that the moon is perpendicular to.

Smaller, rolling tides exist as riptides, where water recedes, then immediately produces a wave that "crashes" upon the area of difference.