The Boeing 767 is a wide-body airliner developed and manufactured by Boeing Commercial Airplanes. The airliner was launched as the 7X7 project on July 14, 1978, the prototype first flew on September 26, 1981, and it was certified on July 30, 1982. The original 767-200 entered service on September 8 with United Airlines, and the extended-range 767-200ER in 1984. It was stretched into the 767-300 in October 1986, followed by the 767-300ER in 1988, the most popular variant. The 767-300F, a production freighter version, debuted in October 1995. It was stretched again into the 767-400ER from September 2000.