While the concept of black holes has become a cultural phenomenon thanks to movies such as Interstellar, it still seems like the general public knows very little about them. In order to help clarify any misunderstandings, welcome to a brief introduction on black holes. In essence, a black hole consists of a massive amount of mass jam-packed into a tiny volume. In order to get a better understanding of this, NASA offers a simple example: for a start 10 times the mass of our sun, it would have all of its mass packed inside of a sphere the diameter of New York City in order to create a black hole. This unbelievably large density is able to prevent anything, even light, from escaping its radius. But how does this work?
The answer is simple physics. Take the equation given above for the escape velocity of an object attempting to escape the gravitational pull of another object. As you can see, there is no bound to the escape velocity. Therefore, when the mass is large enough and the radius is small enough, the escape velocity can surpass the speed of light. Since nothing is faster than the speed of light, nothing will be able to escape within the given radius. And that is a short tutorial on the functionality of black holes.