A Hazard and Operability Study (HAZOP) is a systematic, structured technique for identifying hazards and operability problems in complex systems. Originally developed for chemical process industries, HAZOP has since become a cornerstone of process safety management across various sectors—from oil and gas to pharmaceuticals and nuclear power. This article explains the origins, principles, and step‐by‐step methodology of HAZOP, along with its advantages, limitations, and applications.