A supersonic aircraft is an aircraft that is able to fly faster than the speed of sound, which is Mach number 1. Based on speed an aircraft can be categorized as subsonic aircraft, transonic aircraft, supersonic aircraft, and hypersonic aircraft.

Subsonic aircraft are those which fly at a speed less than the speed of sound. Transonic aircraft are those which are flying near the speed of sound. It is around Mach number 0.8 to 1.2. Hypersonic aircraft are those which can fly above Mach number 5.

Supersonic aircraft of higher Mach number develops shock waves and expansion waves where local air densities, temperature, and pressure varies due to compressibility effects. These aircraft have specialized inlet systems that bring high speed air into the engine. Supersonic aircraft have swept wings in order to reduce drag. Since at higher Mach number, greater than 2.5 there is generation of heat due to frictional heating of air with the airframe, aluminium is not used for the structure. Some other metals which have good high temperature characteristics like titanium can be used.

Supersonic aircraft which fly Mach number less than 2.5, there is a lower frictional heating of the airframe by the air, here aluminium can be used for the structure. Type of engines used for supersonic aircraft are turbojet engines, or low bypass turbofans engines. Ramjet engines can also be used, but it needs to be started at a higher flying velocity.

The first supersonic aircraft was the Bell X-1 experimental plane. Supersonic airplanes at present find their large usage in military fighter aircraft. For commercial aircraft needs to be environmental and economically viable. Concord was the first supersonic commercial aircraft. Boom supersonic, Aerion supersonic and Spike aerospace are some of the aerospace companies which are working on future supersonic passenger aircraft.