Delve into the fascinating world of supermassive black holes in this comprehensive graduate-level lecture. Explore current theories on the formation of seed black holes, accretion processes driving their growth, and the impact on their surrounding environment. Learn about key concepts including the Schwarzschild solution, mass distributions of different black hole types, and the physics of accretion discs. Examine observational evidence for stellar mass black holes, intermediate-mass black holes, and the potential existence of primordial black holes. Gain insights into modeling techniques for accreting sources, including Bondi-Hoyle Lyttleton accretion and disc formation. Understand the Eddington limit, emitted spectra of accreting objects, and the universal nature of accretion discs across various cosmic scales.