The first Airbus plane was the A300, the world's first twin-engined aircraft to have two aisles. A shorter version of the A300 is called the Airbus A310. Airbus launched the A320, which is special as it is the first commercial plane to use a digital fly-by-wire control system. The A320 has been, and still is, a very big success. The A318 and A319 are shorter versions, and the A321 is a longer version, of the A320. The A320's main rival is the Boeing 737 family.