Black Holes: Gateway to the Extreme Universe

Black holes are some of the most interesting and extreme objects in the universe. They are areas in spacetime where gravity is so strong that nothing can escape, not even light. This review provides an overview of black hole physics. It covers their basic ideas in general relativity, the different types of black holes based on mass, and how they form. Recent discoveries are especially notable, including the first direct image of a black hole taken by the Event Horizon Telescope and the detection of gravitational waves from black hole mergers by LIGO and Virgo. These findings have opened new paths in astrophysics. They give us a better understanding of spacetime, high-energy events, and how galaxies evolve. However, many questions still need answers. We still do not fully understand singularities, the fate of information, or if primordial black holes exist. This paper highlights what we know now, the challenges we face, and what the future may hold for black hole research.