GW170817 is a significant astronomical event that occurred on August 17, 2017. It was the first observed merger of two neutron stars, which are incredibly dense remnants of massive stars. This event was detected by gravitational waves, ripples in spacetime predicted by Albert Einstein's theory of general relativity. The merger produced a burst of gamma rays, observed by satellites like Fermi and Swift. It also led to the creation of heavy elements, such as gold and platinum, which were later detected in the aftermath. GW170817 marked a milestone in multi-messenger astronomy, combining gravitational wave and electromagnetic observations.