Final answer:
Tides are caused by the gravitational forces of the Moon and the Sun. Spring tides, the highest tides, occur when the Earth, Moon, and Sun are aligned during a new or full moon. Neap tides, the lowest tides, occur when the Earth, Moon, and Sun form a right angle.
Step-by-step explanation:
Tides are produced by the gravitational forces exerted by the Moon and, to a lesser extent, the Sun, on the Earth's oceans.
When the Moon is on one side of Earth, its gravity pulls water toward it, creating a bulge, which is the high tide. Simultaneously, on the opposite side of Earth, water is also pulled to create another high tide due to the Earth being pulled toward the Moon more than the water on the far side.
This is why we experience two high tides in approximately 24 hours.
The highest tides, known as spring tides, occur when the Sun, Moon, and Earth are aligned during the new moon or full moon.
On the other hand, neap tides, which are the lowest, happen when the Sun and Moon form a right angle relative to Earth (first quarter or last quarter of the moon). The alignments of the Sun and Moon either amplify or partially cancel out the tidal effects, respectively.