There are four types of black holes and it all depends on their mass to differentiate them. The first type is called a primordial black hole. A primordial black hole is the smallest compared to the other three types of black holes. Since primordial black holes are only hypothetical, there are only theories about how they form. It is widely believed that these primordial black holes formed very early in the Universe, just after the Big Bang. An important factor in its formation is the fluctuation in the density of the Universe. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get an Original Essay The second type is called a stellar black hole. Stellar black holes have masses that can reach up to 20 times that of the sun. Initially, the core of a high-mass star will be completely reduced to iron. At this point, energy production stops and the star's core rapidly collapses, causing a supernova explosion. If the star's core is larger than about 2-3 solar masses (the maximum mass of a neutron star), the neutron pressure will be unable to stop the collapse and thus result in a stellar black hole. The third type is called a supermassive black hole. These black holes can contain between a million and a billion times more mass than a typical stellar black hole. There are only a handful of confirmed supermassive black holes, as most of them are too distant to observe. However, according to astronomers, there is a supermassive black hole located at the center of the Milky Way. The name given to this black hole is “Sagittarius A*”. To put the size of Sagittarius A* into perspective, its mass is equivalent to about 4 million suns. To date, there are only theories about the formation of supermassive black holes. Astronomers believe that once a black hole forms in the galaxy, it may grow through accretion of matter or merge with other black holes which, in turn, form a supermassive black hole. However, a popular theory is that supermassive black holes formed as a result of the collapse of massive gas clouds during the early stages of galaxy formation. Keep in mind: this is just a sample. Get a personalized article from our expert writers now. .Get a Custom EssayThe last type is called an intermediate mass black hole. Throughout history, astronomers believed that black holes only came in two sizes. Both being stellar black holes and supermassive black holes, as mentioned earlier. However, recent evidence from the Chandra X-ray Observatory, XMM-Newton (X-ray space observatory), and Hubble (space telescope) strengthens the hypothesis that medium-sized black holes exist. The first possible theory for the formation of intermediate mass black holes (IMBHs) is that they form by the collapse of population III stars (the first generation of stars to form in the early stages of the universe) . The second possible theory is that IMBHs form from collisions of massive stars or black holes inside star clusters..