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What is a black hole-and how can it trap light? On Earth, gravity pulls things toward the ground. But a black hole isn't an empty gap in space. It's a region where gravity is far more extreme. Here's the surprising part: matter packed into a tiny space can make gravity strong enough to trap light. Around it is a boundary called the event horizon: cross it, and light cannot escape. That boundary isn't a solid wall; it marks the point from which escape is no longer possible. But a black hole doesn't suck in everything nearby. You don't get pulled in just for being nearby. Stay far enough away, and objects can orbit it safely, just as planets orbit the Sun. So what is it? A region of space where gravity is so powerful that, beyond its boundary, even light cannot get out.