Black holes are among the most intriguing objects in modern physics, influencing phenomena such as quasars and active galactic nuclei, and providing insights into quantum gravity. They are formed when sufficient mass is compressed into a small volume, creating a region of spacetime from which nothing can escape. Observational evidence for black holes includes the maximum mass of neutron stars, the compactness of black holes, and the Eddington limit. Supermassive black holes, with masses up to $10^9 M_{\odot}$, are found at the centers of galaxies. X-ray binaries and quasars provide further evidence, with black holes identified by their high mass and compactness. Recent developments include the statistical origin of black hole entropy and cosmic censorship, which posits that singularities are hidden behind event horizons. The uniqueness of black holes is highlighted by the "no hair" theorem, which states that they are characterized only by mass, charge, and angular momentum. Quantum mechanics has shown that black holes have thermodynamic properties, with temperature and entropy given by $T_{bh} = \hbar \kappa / 2\pi$ and $S_{bh} = A / 4\hbar$. String theory and canonical quantization of general relativity support this, showing that the number of BPS states matches the entropy of black holes. The study of black holes connects to various fields of physics, offering insights into quantum gravity and the nature of spacetime. Current research aims to verify the existence of black holes through gravitational wave observations and other astrophysical evidence.Black holes are among the most intriguing objects in modern physics, influencing phenomena such as quasars and active galactic nuclei, and providing insights into quantum gravity. They are formed when sufficient mass is compressed into a small volume, creating a region of spacetime from which nothing can escape. Observational evidence for black holes includes the maximum mass of neutron stars, the compactness of black holes, and the Eddington limit. Supermassive black holes, with masses up to $10^9 M_{\odot}$, are found at the centers of galaxies. X-ray binaries and quasars provide further evidence, with black holes identified by their high mass and compactness. Recent developments include the statistical origin of black hole entropy and cosmic censorship, which posits that singularities are hidden behind event horizons. The uniqueness of black holes is highlighted by the "no hair" theorem, which states that they are characterized only by mass, charge, and angular momentum. Quantum mechanics has shown that black holes have thermodynamic properties, with temperature and entropy given by $T_{bh} = \hbar \kappa / 2\pi$ and $S_{bh} = A / 4\hbar$. String theory and canonical quantization of general relativity support this, showing that the number of BPS states matches the entropy of black holes. The study of black holes connects to various fields of physics, offering insights into quantum gravity and the nature of spacetime. Current research aims to verify the existence of black holes through gravitational wave observations and other astrophysical evidence.