Tides are the regular rise and fall of sea levels caused by the gravitational pull of the Moon and the Sun on the Earth's oceans. As the Earth rotates, different areas experience these changes, leading to high and low tides approximately every six hours. The cycle of tides is influenced by the positions of the Moon and Sun relative to the Earth. During a full moon or new moon, tides are higher and lower than usual, known as spring tides. Conversely, during the first and third quarters of the moon, tides are less extreme, called neap tides.