Stellar mass black holes as compared to super massive black holes are smaller in size and have low mass. As mentioned in previous article, stars are the main ingredient in the formation of stellar size black holes, but not every star can make a black hole. It is theoretically proved that stars with the mass of at least three times the mass of the sun can collapse and form stellar mass black holes. The collapse of a star is a natural process and occurs due to the combustion of all the fuel by fusion reaction.
When all the hydrogen in the core of a star is burned, then the gravity of the star overcomes the nuclear force. Nuclear force is the force that forces electrons and atoms to stay together, but when gravity of the star wins then it causes a huge explosion. Smaller stars end up with a white dwarf, but massive stars at the end of their life forms black holes. If the mass of the star is below than three solar masses, then it will end with a white dwarf or a neutron star. Stars with higher masses end up with forming stellar mass black holes. Black holes consume gas and dust in the surroundings which causes increase in their sizes.
So far black holes were categorized as a stellar black holes and super massive black holes, but recent evidence demonstrates that a middle figure of black holes also exists. Super massive black holes are formed by collapse of more than one stellar mass black hole. Under equations of physics nothing can escape from the event horizon of a black hole, but in the case of quantum mechanics there is always an antiparticle for every particle with the same mass but opposite charge. When a particle and antiparticle is produced just beyond event horizon, it is possible that one have drawn in while another is ejected which can cause decay of black holes. Under classical mechanics, it is not possible.
Our galaxy has many black holes, which were formed by the collapse of massive stars. The world of black hole is full of wonders like some say singularity of a black hole is way into another dimension but nothing like that have been proven yet. One thing is quite sure that complete understanding of a black hole can reveal many unknown secrets of our universe.