Umbra

Real World Example

Imagine trying to find your car keys in a cluttered drawer where everything seems to blend together. Just as the keys can be hidden in the darkest corner of the drawer, the umbra is the darkest part of a shadow where no light can reach. In both cases, the key and the umbra are surrounded by lighter, more visible areas—the clutter in the drawer or the penumbra of the shadow—making them hard to notice without careful attention.