Why is the Earth considered a geoid?

What is the shape of the Earth?

The Earth is considered a geoid, which is a slightly flattened sphere.

The Earth is considered a geoid because of its shape.

The Earth is not a perfect sphere due to its rotation. The rotation causes the equator to bulge outward, making the Earth slightly flattened at the poles and bulging at the equator. This shape is known as a geoid. The geoid shape represents the shape that the Earth's oceans would take under the influence of Earth's gravity and rotation alone, without any other forces such as tides or winds affecting it.

Therefore, the Earth is considered a geoid because it is a three-dimensional representation of the Earth's gravity field, taking into account the Earth's irregular shape caused by its rotation.