The first thing that comes to mind when thinking about tides is the lunar tides that create 2 high and low tides each day. This is due to daily rotation of the Earth, which causes the Moon to effectively move around the Earth every day. The Moon’s gravitational force pulls the water from the sides of the Earth towards the part that is facing the Moon, which creates higher water levels on the side of the Earth facing the Moon, as well as the side opposite the Moon. The moon, however, is not the only celestial body that has a gravitational pull on the Earth. While the Sun is significantly more massive than the Moon, it is much farther away, so its gravitational pull on the Earth is lesser than that of the Moon. Since the positions of the Sun and Moon are not always perfectly aligned relative to the earth (they rarely are), there is also a cycle of high and low tides affected by the position of the sun. These are called spring and neap tides. Spring tides occur when the Sun’s gravitational pull is in the same general direction as the Moon’s, causing high tides to be higher and low tides to be lower. Neap tides occur when the Sun’s gravitational pull is in the opposite direction of that of the Moon, causing high tides to be lower and low tides to be higher. Another interesting occurrence is the Proxigean Spring Tide, which occurs when the Moon is unusually close to the Earth during a spring tide. This occurrence creates a “super tide” where especially high and low tides occur.
Sources: The Moon and Tides