Stellar black holes are formed when massive stars exhaust their nuclear fuel and undergo gravitational collapse. This process results in a region of space where the gravitational pull is so strong that nothing, not even light, can escape. These black holes typically have masses ranging from about three to several tens of solar masses, making them significantly smaller than supermassive black holes found at the centers of galaxies. The study of stellar black holes provides insights into the life cycles of stars and the dynamics of galaxies. They are often detected through their interactions with nearby matter, such as gas from companion stars, which can emit X-rays as it spirals into the black hole, creating observable phenomena that astronomers can study.