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In 2019, the Event Horizon Telescope (EHT) collaboration released the first image of a supermassive black hole: the one residing at the center of the galaxy M87. Since that milestone, the EHT has established a rich legacy that includes the first images of Sagittarius A*, the black hole at the center of the Milky Way; the first images of black hole environments in polarized light—both linear and circular—revealing dynamically important magnetic fields near the event horizon and favoring magnetically arrested disk models; and the first strong evidence for intrinsic time variability in both total intensity and magnetic field structure. In this colloquium, I will review these key scientific results and discuss the evolution of the EHT array that made them possible. I will conclude by describing ongoing developments and future efforts aimed at obtaining the first time-resolved “movie” of a black hole, probing horizon-scale dynamics on timescales comparable to the characteristic timescales of the system.