A black hole is an object that consists of a very large mass in a very small space, creating gravity so strong that nothing – including light – can get out of it. It is essentially an area of space that is curved so much that anything that comes near it is irrevocably trapped by its gravity. A black hole is formed when a very massive star collapses at the end of its life cycle and its mass is concentrated into a very small space. The size of the black hole depends on the mass of the original star. Black holes can also form from the merger of several stars or result from other causes.
There are several types of black holes, such as stellar black holes, which form from collapsed stars, and supermassive black holes, which are found at the centers of galaxies and can be millions to billions of times the mass of the Sun. Although black holes seem scary due to their strong gravity, they are important objects in astrophysics and help us expand our understanding of space, time and the nature of gravity.