Airport inspection and security screening are the primary defenses against "unlawful interference" with civil aviation, including terrorism, sabotage, and the transport of hazardous materials. Since the events of 9/11, these inspections have evolved into a multi-layered system designed to detect weapons, explosives, and prohibited items before they enter the "sterile" area of the terminal or the aircraft cabin. Beyond physical safety, inspections also serve a biosecurity and customs role, preventing the illegal movement of plants, animals, and currency that could damage a nation's economy or ecosystem. By standardizing these checks globally, airports ensure a "chain of trust" that allows thousands of aircraft to move safely between borders every day, maintaining public confidence in the safety of the global air travel network.