The Earth's shape is best described as an oblate spheroid.

Here's why:

* Sphere: The Earth is close to a sphere, meaning it's round in all directions.

* Oblate: It's slightly flattened at the poles and bulging at the equator. This is due to the centrifugal force created by the Earth's rotation.

So, while a sphere is a good starting point, "oblate spheroid" is the most accurate way to describe the Earth's shape.