Black holes exist due to the gravitational collapse of massive stars. When these stars exhaust their nuclear fuel, gravity overcomes the forces supporting the star, causing it to collapse under its immense weight. This collapse creates a region of spacetime where gravity becomes infinitely strong, known as a singularity, surrounded by an event horizon, beyond which nothing can escape, not even light. Black holes are a consequence of the fundamental laws of general relativity and have been confirmed through astronomical observations. They play a crucial role in astrophysics and our understanding of spacetime and gravity.