A black hole is like a cosmic vacuum cleaner. It's an incredibly dense and heavy object in space that sucks in everything, including light, and nothing can escape from it once it gets too close. It's formed from the remains of massive stars that collapsed.
Black holes exist because of the way massive stars evolve and end their lives. When a massive star (many times bigger than our Sun) runs out of nuclear fuel, it can no longer support its own gravity. This leads to a collapse inward, and if the star is massive enough, this collapse can continue until it forms a black hole.
In simple terms, think of it like a balancing act between the outward pressure from nuclear reactions (which keeps the star from collapsing) and the inward pull of gravity (which tries to make the star collapse). When the nuclear reactions stop, gravity wins, and the star implodes, forming a black hole.
So, black holes exist as a natural consequence of the life cycle of massive stars. They are a fascinating outcome of the laws of physics and the way the universe works.