The areas of high water levels are high tides and the areas of low levels are low tides. Since the earth and the moon rotate around the sun, there is an added modifying factor. 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.
Tides vary from day to day.
As the earth, moon, and sun orbit, their positions constantly shift, causing slightly different gravitational effects. This causes the tides to occur at slightly different times. Tides also vary from place to place. Geographical position determines the level of tide. In Northern California there are two unequal tides each day.