A nacelle is a streamlined structure that houses important components of an aircraft or wind turbine. In aircraft, it typically contains the engines, fuel systems, and sometimes the crew. The design helps reduce drag and improve aerodynamics, contributing to better performance and efficiency. In wind turbines, the nacelle is located at the top of the tower and contains the generator, gearbox, and other mechanical parts. It plays a crucial role in converting wind energy into electrical energy. The nacelle's design ensures that these components are protected from the elements while allowing for optimal operation.