Swift is the first satellite explicitly designed to solve the mystery of gamma-ray bursts, the enigmatic explosions that have puzzled astronomers for decades. Practically every day, another burst randomly appears in the sky, flashing powerful gamma rays for anywhere from a fraction of a second to two minutes. Before the burst fades, Swift quickly locates it, rotates its telescopes and other satellites for observation, and relays the burst's location to ground-based telescopes, which study it in detail.