Gas Insulated Switchgear (GIS) is a compact and reliable electrical system used in medium- and high-voltage substations for power distribution, control, and protection. It uses SF6 gas as an insulating medium to prevent electrical faults and ensure safe operation. GIS consists of several main components, including Circuit Breakers (CB), Disconnectors (DS), Earthing Switches (ES), Busbars, Current Transformers (CT), and Voltage Transformers (VT). The system provides high operational reliability, requires less installation space, and reduces maintenance compared to conventional Air Insulated Switchgear (AIS). Regular monitoring of SF6 gas pressure, gas density, and equipment condition is essential to maintain safe and efficient operation.