Run the animation, varying the distance from the red bead to the white screen to see the definition of the two parts of a shadow.
The umbra is the region of full shadow cast by the bead, while the penumbra is the region of partial shadow. On the white screen, the bead's umbra is the dark central circle and the penumbra is the lighter grey area around that. In the umbra the light is completely blocked; in the penumbra the light is only partly blocked.
Why is there no umbra, only a penumbra, when the white screen is as far to the right in the animation view as possible?