What is a shadow?

The video explains the concept of shadows, starting with a riddle about what is short and disappears in the dark. It then describes how shadows are formed when an object blocks light, creating a darker area behind it. Various examples are provided, including an igloo, a pyramid, a cactus, an eagle, and a reindeer, each casting shadows in different environments. The video concludes by explaining how personal shadows are formed when individuals block light.

What new insight or understanding did you gain from this video?