Final answer:
Most coastlines on Earth experience two high tides and two low tides each day due to the Moon's gravitational force on the Earth and the rotation of the Earth.
Step-by-step explanation:
In an idealized model, most coastlines on Earth experience two high tides and two low tides each day. This is due to the Moon's gravitational force on the Earth, which causes ocean water to flow into two tidal bulges on opposite sides of the Earth. As the Earth rotates, locations on its surface pass under these bulges, resulting in two high tides and two low tides. The actual timing of the tides is influenced by various factors, including the Sun's gravitational force.