The Douglas DC-9 is a twin-engine, short- to medium-range jet airliner that was first introduced in 1965. Designed by McDonnell Douglas, it features a T-tail configuration and can accommodate up to 130 passengers. The aircraft was known for its reliability and efficiency, making it popular among airlines for domestic routes. Over its production run, which lasted until 1982, more than 900 units of the DC-9 were built. Variants of the aircraft include the DC-9-10, DC-9-30, and DC-9-50, each offering different capacities and range. The DC-9 has been succeeded by newer models, but it remains a significant part of aviation history.