Lost is an American serial drama television series. It follows the lives of plane crash survivors on a mysterious tropical island, after a commercial passenger jet flying between Sydney, Australia, and Los Angeles, United States, crashes somewhere in the South Pacific. Each episode typically features a primary storyline on the island as well as a secondary storyline from another point in a character's life, though other time-related plot devices change this formula in later episodes

The series began development in January 2004, when Lloyd Braun, head of ABC at the time, ordered an initial script from Spelling Television based on his concept of a cross between the novel Lord of the Flies, the movie Cast Away, the television series Gilligan's Island, and the popular reality show Survivor. ABC had also premiered a short lived series about plane crash survivors in 1969 called The New People with the opening episode by Rod Serling. Gadi Pollack notes that some of "the influences of Lost came from...the game Myst."^[16] Jeffrey Lieber was hired and wrote Nowhere, based on his pitch to write the pilot.^[17] Unhappy with the result and a subsequent rewrite, Braun contacted J. J. Abrams, who had a deal with Touchstone Television (now ABC Studios), and was also the creator of the TV series Alias, to write a new pilot script. Although initially hesitant, Abrams warmed up to the idea on the condition that the series would have a supernatural angle to it, and collaborated with Damon Lindelof to create the series' style and characters.^[18] Together, Abrams and Lindelof also created a series "bible", and conceived and detailed the major mythological ideas and plot points for an ideal five to six season run for the show.^[19][20] The development of the show was constrained by tight deadlines, as it had been commissioned late in the 2004 season's development cycle. Despite the short schedule, the creative team remained flexible enough to modify or create characters to fit actors they wished to cast.^[21]

Lost's two-part pilot episode was the most expensive in the network's history, reportedly costing between US$10 and $14 million,^[22] compared to the average cost of an hour-long pilot in 2005 of $4 million.^[23] The series debuted on September 22, 2004, becoming one of the biggest critical and commercial successes of the 2004 television season. Along with fellow new series Desperate Housewives and Grey's Anatomy, Lost helped to reverse the flagging fortunes of ABC.^[24] Yet, before it had even been aired, Lloyd Braun was fired by executives at ABC's parent company, Disney, partly because of low ratings at the network and also because he had greenlighted such an expensive and risky project.^[18] The world premiere of the pilot episode was on July 24, 2004 at Comic-Con International in San Diego.^[25]

The aircraft used as Flight 815, although described as a Boeing 777-200ER, is actually a Lockheed L-1011 TriStar, formerly flown by Delta Air Lines as N783DL. The plane was bought by ABC/Touchstone and was broken up, and all except the tail was shipped to Hawaii, fearing that the viewers might recognize the real identity of the aircraft, since the L-1011 was a tri-jet. However, with the plane broken up, it was seen as a Boeing 767-400.