Tide means the rising and falling of the sea level.
High tide is a period in which the sea experiences the highest level of tide rise. High tide is caused due to gravitational pull known as tidal force, when this occurs the effect it has is that it makes the earth and water to erupt from the side closest to the moon and the side far away from the moon. This water eruption is what is called high tides. It is caused by the moon and it directly has to do with gravity, high tide is a results of gravitational pull.
