According to the Bible, in the beginning, the earth was unformed and void. But in Unity, it starts as an untextured sphere. 3D objects in Unity, such as spheres, cubes, or arbitrarily shaped meshes, are rendered by default using an untextured default material.
Materials define the details of how the surface of an object should look, usually using texture images. A texture is an image that is mapped onto the surface of an object as if it were painted or was a wallpaper. This is referred to as the Albedo texture or surface reflection. Advanced materials can use other textures to simulate additional surface detail, bumps, rust, metals, and other physical characteristics.
Suppose a sphere had a surface texture like this:
