If you've kept an eye on the Game view, which is what the player sees, you've noticed that the Mesh Game Objects in our Scene are a dark, dreary gray color. Would you believe me if I told you they're actually closer to white?

Just like on a real movie or teevee set, 3D scenes require lights to illuminate objects. The lights aren't actually "real" objects (like our Ball and Paddle meshes), they're virtual objects in 3D space that determine whether the faces on a mesh will appear bright or dark. The computer figures this out for us based on the kind of light we use, the way we position and rotate it, and the settings we give it.

So, while you can move a light around your scene just like the Ball or the Paddle, there's no actual geometry or triangles comprising the light. Lights aren't made of triangles, they're made of data. In Unity, as in many 3D programs, lights are represented by icons (or as Unity calls them "gizmos"), with lines indicating their direction or their area of influence.