One of the most striking predictions of the general theory of relativity is the formation of black hole and cosmic horizons sequestering different regions of spacetime. In this talk we will overview recent theoretical and observational developments in this area. At the classical and quantum level, radiation plays an important role in observations and thought experiments. Hawking’s result that black holes radiate raises serious puzzles, while its analogue in early universe cosmology yields a successful quantum theory of the origin of structure. The pursuit of a complete theory of quantum gravity has led to qualitatively new lessons about emergent spacetime structure in the presence of horizons. Turning to observations, the proposition that black holes with masses from three to ten billion times that of the sun are quite common in the universe grew from a conjecture to a conviction. Recent observations using the Fermi Gamma-ray Space Telescope, LIGO/VIRGO and the Event Horizon Telescope have validated general relativity and demonstrated how black holes are born, how they affect their surroundings and how they power the most luminous cosmic sources.