The Great Gatsby was written by the American author F. Scott Fitzgerald and published in 1925.
It is set among the lavish millionaires' homes of Long Island. This is a lifestyle and environement that Fitzgerald knew well. His own family background, though well off at first, was not super rich, but after dropping out of university, a spell in the army and other ventures, in 1920 he married the beautiful young socialite Zelda Sayre, and through her, and later through his own literary fame, he came in contact with the kind of people and places that are described in The Great Gatsby.
Rather like Gatsby, Fitzgerald felt like an outsider among these privileged and glamorous people. Gatsby pretends to be upper class but is in fact from a poor background and has made his money by shady means.
Although Fitzgerald wrote many other novels and stories, Gatsby is usually seen as his masterpiece. In his own lifetime, after a period of fame in the 20s and 30s, he was almost forgotten, but his fame has grown steadily since.