PMU placement refers to the placement of Phasor Measurement Units (PMUs) in an electrical power system in order to monitor and analyze the system's performance. PMUs are devices that measure the voltage, current, and frequency of electrical signals at various points in the system with high accuracy and precision. The placement of PMUs is crucial for ensuring the reliability and stability of the power system, as they provide real-time data on the state of the system and can help identify and locate issues such as voltage instability, line overloads, and disturbances. Researchers in the field of PMU placement focus on developing algorithms and methodologies to determine the optimal locations for installing PMUs in order to maximize the observability and controllability of the power system. This involves considering factors such as network topology, measurement redundancy, and cost-effectiveness. Overall, PMU placement research plays a key role in enhancing the situational awareness and control capabilities of power systems, ultimately improving their efficiency, reliability, and resilience.