Scientists at CERN’s NA62 collaboration have observed the ultra-rare decay of a charged kaon into a charged pion and a neutrino-antineutrino pair (K+ → π+νṽ), a process predicted by the Standard Model to occur in less than one in 10 billion kaons. This discovery, presented at a CERN EP seminar, marks the rarest decay established at the 5 sigma discovery level. The NA62 experiment, designed to measure this decay, utilized a high-intensity proton beam and advanced detectors. The result combines data from 2016-18 and 2021-22, following significant upgrades to the NA62 setup.