The Airbus A320 family is a family of short- to medium-range, narrow-body, commercial passenger jet airliners manufactured by Airbus. The family includes the A318, A319, A320, and A321, as well as the ACJ business jet. The first member of the A320 family, the A320, was launched in March 1984, first flew on 22 February 1987, and was first delivered in 1988. The family was soon extended to include the A321 (first delivered 1994), the A319 (1996), and the A318 (2003). The A320 family pioneered the use of digital fly-by-wire flight control systems in a commercial aircraft. Although there were a continuously improvement process since introduction, currently the A320 Enhanced program includes greater improvements. The Airbus A320 family has over 4,200 built and an additional 2,300 on order as of March 2010. According to Airbus, it ranked as the world's fastest-selling jet airliner family according to records from 2005 to 2007, and the best-selling single generation aircraft programme.