Supermassive black holes: Characteristics and formation

Only a handful of supermassive black holes have been confirmed by scientists, but the universe could be filled with billions of these gravitational giants. 

Theoretically, if you compress a sufficient amount of matter into a small enough space, it will create such a powerful gravitational field that nothing — not even light — can escape from it. That’s the basic idea behind black holes, and it’s so bizarre that for many years people thought they couldn’t possibly exist in reality, according to University of Texas in Austin.