How does the Moon's gravity affect Earth's tides?

The Moon's gravity pulls on Earth's water, causing bulges on the side closest and farthest from the Moon, creating tides.

The Moon's gravitational pull is the primary force driving the tides on Earth. This is due to the gravitational attraction between the Earth and the Moon. The Moon's gravity pulls on every part of the Earth, but it pulls harder on the side of the Earth closest to the Moon because it's closer. This causes the water on this side to bulge out towards the Moon, creating a high tide.

On the opposite side of the Earth, farthest from the Moon, there's also a high tide. This might seem counterintuitive, but it happens because the Earth itself is also being pulled by the Moon's gravity, more so than the water on the far side. This means the Earth is pulled away from the water on that side, creating another bulge and hence another high tide.

In between these two high tides, the water is drawn away, creating areas of low tide. As the Earth rotates, different areas move into these bulges, experiencing high and low tides. This is why most places have two high tides and two low tides each day.

The Sun also affects tides, but to a lesser extent than the Moon due to its greater distance from the Earth. When the Sun, Moon, and Earth are aligned (during a full moon or new moon), the gravitational pull of the Sun adds to that of the Moon, causing especially high and low tides known as spring tides. When the Sun and Moon are at right angles to each other (during the first and third quarter moon), their gravitational pulls partially cancel each other out, resulting in less extreme tides known as neap tides.