The Airbus A321 is a member of the Airbus A320 family of short- to medium-range, narrow-body, commercial passenger twin-engine jet airliners manufactured by Airbus. It was the first derivative of the baseline Airbus A320 aircraft, and carries up to 236 passengers with a maximum range of 3,200 nmi (5,900 km; 3,700 mi). Final assembly of the aircraft takes place in Hamburg, Germany or Mobile, Alabama in the US.

The A321 is a stretched-fuselage variant of the Airbus A320 and entered service in 1994 with Lufthansa, around six years after the original A320. The aircraft shares a common type rating with all other Airbus A320 family variants, allowing existing A320 family pilots to fly the aircraft without the need for further training.

As of 30 November 2016, a total of 1,413 Airbus A321 aircraft have been delivered, of which 1,396 are in service. In addition, another 320 airliners are on firm order. As of 30 November 2016, American Airlines was the largest operator of the Airbus A321, operating 197 aircraft.

In December 2010, Airbus announced a new generation of the A320 family, the A320neo (new engine option). The similarly lengthened fuselage A321neo variant offers new, more efficient engines, combined with airframe improvements and the addition of winglets, named Sharklets by Airbus. The aircraft will deliver fuel savings of up to 15%. The A321neo has total orders for 1,376 aircraft as of 30th November 2016.

The A321LR is a proposed long-range variant of the A321neo, which Airbus predicts provides an overall 25–30% lower operating cost than the Boeing 757 on routes of up to 4,100 nmi (7,600 km; 4,700 mi) where a wide-body would be uneconomical.

Dimensions: 17.9 x 22.3 x 6.1 cm