What are the different types of shadows?

There are three main types of shadows: umbra, penumbra, and antumbra. The umbra is the darkest part of a shadow, where the light source is completely blocked; the penumbra is the lighter, outer part where the light is partially obscured; and the antumbra occurs when the light source appears larger than the object casting the shadow, creating a lighter shadow that may have a halo effect. These types can vary based on the position of the light source and the object in relation to it.