TLDR: Aircraft are vehicles that can fly by using the air to support them. They can be airplanes, helicopters, airships, gliders, and more. Aviation is the activity that involves aircraft, and aeronautics is the science of designing and building them. Aircraft can be classified in different ways, such as by their lift type, propulsion method, and usage.

Aircraft have a long history, with the first manned flight taking place in the 18th century using hot-air balloons. The development of aircraft was greatly accelerated by the two World Wars, leading to advancements in technology and design. The history of aircraft can be divided into five eras: pioneers of flight, World War I, aviation between the World Wars, World War II, and the postwar era.

There are different methods of lift that allow aircraft to fly. Lighter-than-air aerostats, such as balloons and airships, use buoyancy to float in the air. Heavier-than-air aerodynes, such as airplanes and helicopters, use wings or rotors to generate lift. Fixed-wing aircraft rely on the forward movement of wings, while rotorcraft use spinning rotors to provide lift. There are also other methods of lift, such as lifting bodies and powered lift.

Aircraft come in various sizes and speeds. The largest aircraft by dimensions is the Airlander 10, a hybrid blimp capable of speeds up to 90 mph. The largest aircraft by weight is the Antonov An-225 Mriya, a six-engine transport plane. The fastest aircraft include the Space Shuttle, the X-43A experimental aircraft, and the Lockheed SR-71 Blackbird.

Aircraft can be powered or unpowered. Powered aircraft have engines that provide thrust, such as propeller engines or jet engines. Unpowered aircraft, such as gliders and balloons, rely on external forces like wind or gravity for propulsion. The structure of an aircraft can vary depending on its type, with aerostats having gasbags or hulls, and aerodynes having wings and fuselages.

Designing and constructing aircraft involves considering factors like safety, customer demand, and physical and economic constraints. The structure of an aircraft can be made of flexible materials or rigid frames, depending on the type of aircraft. The powerplant of an aircraft includes the engine, propeller or rotor, and other components necessary for its operation.

In summary, aircraft are vehicles that can fly by using the air for support. They come in different types, sizes, and speeds, and can be powered or unpowered. The design and construction of aircraft involve considering various factors, and the structure and powerplant of an aircraft depend on its type.