The chapter introduces efficiency indicators for a commercial airliner, discusses and compares the features of airliner’s aerodynamic configurations, the potential of increasing its size and weight, and promising innovative layouts, such as multi-deck fuselages, “tailless,” and “flying wing” aircraft. The chapter also provides details of the design of passenger cabins, emergency and safety equipment, baggage and cargo compartments, galley, and lavatory. The chapter introduces a method for defining the optimal cruise speed and thrust capacity for a typical commercial airliner. The last part of the chapter is devoted to the features of supersonic passenger aircraft, including the issues of aerodynamic heating and sonic boom.