Decommissioning is the final stage in the lifecycle of a nuclear facility. It is a complex process that begins after the end of operation of a nuclear power plant or other nuclear installation. Its objective is to safely remove radioactive materials and reduce residual hazards while protecting workers, the public, and the environment. The entire process must comply with strict safety and regulatory requirements and often continues for decades. Decommissioning involves many technical, organizational, and environmental challenges including the handling of activated materials and radioactive waste. Modern projects increasingly use advanced technologies such as remotely operated systems, robotic manipulators, laser cleaning, and various thermal and mechanical cutting techniques.