Oil. The Black Gold of the Earth

Why is oil called "black gold"? When was it discovered? How is it extracted? 

Oil is not only the well-known gasoline, but also furniture, toys, packaging, cosmetics, and even medicines. 

Let's figure out why oil occupies such a significant place in human life and what products made from it surround us everywhere, even though we are not always aware of it.
For younger schoolchildren