How do tides work?

Tides are the regular rise and fall of the sea, driven mainly by the gravitational pull of the Moon, with a smaller contribution from the Sun. The Moon gravity tugs the ocean water toward it, creating a bulge on the near side of Earth, while a second bulge forms on the far side. As Earth rotates, coasts pass through these bulges, giving most places two high and two low tides a day. When the Sun and Moon align, their combined pull creates especially large spring tides.