What is a black hole?

The video explains black holes as extremely dense objects from which nothing, not even light, can escape. It describes their formation from large stars that collapse under gravity after exhausting their fuel. Although black holes are invisible, they can be detected by observing their effects on nearby stars, such as emitting x-rays when pulling in material.

What is a black hole and why is it described as something that is so dense?

What happens to a star when it runs out of stellar fuel?

What role does gravity play in the formation of a black hole?

How can black holes be detected if they cannot be seen directly?

What is emitted by material as it moves towards a black hole?