Black Holes - formation

Understanding what a black hole is can be hard or even misleading. It's not just a hole in the universe, it is something more than that. Let's start from the beggining, there are 4 different types of black holes but the most common ones are stellar black holes. Stellar black holes come from starts. When a massive star builds too much iron in it's core the center collapses in upon itself causing big explosion (a.k.a supernova). This explosion can either form a neutron star or a black hole. Second most common black hole is supermassive black hole. Every galaxy has it's own supermassive black hole in it's center. Scientist don't know yet the origin of them but probably they've been created during the big bang. They can be million or even billion times more massive than our sun. The other 2 types of black holes are : intermediate black hole (medium mass) and miniature black hole, i think their names are quite self explanatory.

sources: https://www.youtube.com/watch?v=kOEDG3j1bjs

https://www.youtube.com/watch?v=e-P5IFTqB98