How much do you know about the black hole?

As you have already said blackholes are formed from stars when the stars are collapsing.A Blackhole is a region of space in which the gravitational field is so powerful that even light cannot escape its pull.Its called black because it absorbs everything including light just like a blackbody in thermodynamics. There are many stages in what you call the end of the star and the final stage may result in blackhole. Generally people believe that blackholes are formed by gravitational collapses.these occur when an objects internal pressure is insufficient to resist the objects own gravity. This usually happens in stars when they dont have enough fuel to maintain their temparature so they start collapsing. However all the collapsing stars donot form blackholes.In most cases the collapsing is stopped and a compact star is produced. This collapse is stopped by the degeneracy pressure but however if the star is too big then the collapse will eventually result in a blackhole the theory behind the formation of blackhole is still unknown that is no one can say which star is going to be a black hole but mainly gravitational collapse of heavystars is often believed to be the reason for formation of blackholes. I have written what i know Iam not sure if its true or not so u better seek information from wikipedia or some scientific journals for more valued information