This document summarizes a seminar presentation on black holes. It defines a black hole as a region of spacetime where gravity is so strong that nothing, not even light, can escape. It describes three types of black holes based on size: primordial, stellar, and supermassive. Key properties of black holes are discussed, including the event horizon boundary and singularity at the center. As mass falls into a black hole, its properties like shape and composition vanish. The document also briefly outlines concepts like accretion disks, how black holes generate energy, and limits on their brightness.