When is a shadow formed and why?

Answer 1

A shadow is formed on the side of an object opposite to the side that's being

illuminated by a light source.

The shadow is simply the region where light can't reach because the object is

in the way.

The shadow is not something. It's the region of nothing, surrounded by something.

The shadow is the region where there is no light. In the same way that cold

is not something, it's the absence of heat. And silence is not something, it's

the absence of sound.

I was also about to suggest that stupidity is not something, it's the absence of

something else. But I've decided not to go there just now.