What does a rectangular prong that is larger than the other on a plug ensure?

A rectangular prong that is larger than the other prongs on a plug is designed to ensure good grounding. This specific design, often referred to as a polarized plug, is intentional to prevent incorrect insertion into an electrical outlet. The larger prong connects to the grounding wire of the electrical system, which is essential for safety. Grounding helps to redirect any excess electrical current that may come from a short circuit or malfunction, effectively reducing the risk of electric shock or fire hazards. This measure is an important safety standard in electrical systems, ensuring that devices are properly grounded and minimizing potential dangers during their operation.