HAZOP (Hazard and Operability Study) is a structured, systematic technique for identifying potential hazards and operability problems in a process or system by applying a set of guide words — such as ‘more’, ‘less’, ‘no’, and ‘reverse’ — to each design intention and examining the consequences of deviation. It is widely used in process industries and safety-critical engineering, and is referenced by functional-safety standards such as IEC 61508. A HAZOP study is typically conducted by a multidisciplinary team working systematically through a piping and instrumentation diagram or equivalent process representation.