Firefly is a science fiction television series that premiered on television in the United States and Canada on September 20, 2002. It was created by Joss Whedon of Buffy the Vampire Slayer and Angel fame. Whedon and Tim Minear were the executive producers. The series concept merges the classic "Western" genre with a science fiction backdrop, applying naturalistic science fiction concepts, such as showcasing flawed characters in humble circumstances.

The series was broadcast on the FOX network in 2002 and was cancelled after only eleven episodes. However, strong sales of the DVD collection of all fourteen episodes that were made allowed Whedon to convince Universal Studios to produce a film based on the series, titled Serenity after the crew's spacecraft of the same name.

The series is set in the year 2517. Long before the events in the story, a large population emigrated from the Earth to a new star system in multi-generational ships that traveled much faster than today's ships, but nowhere near light speed (as in various science-fiction shows). The emigrants established themselves in a new star system, with dozens of planets and hundreds of moons, many of which had been "terraformed," a process in which a planet or moon is altered to resemble the Earth. The terraforming process is imperfect, and the outlying settlements are typically set in forbidding, dry environments, well suited to the western genre.

Characters in the story occasionally refer to "Earth that was" suggesting that the original home planet has been somehow destroyed, or is so far out of reach that for them, it is mythical (it is cryptically stated in the opening narration that Earth "got used up", and the humans left).

The show takes its name from the Firefly-class spaceship Serenity that the central characters call home. Somewhat resembling an insect in general arrangement, the ship's tail section (analogous to an insectoid abdomen) lights up during acceleration, causing it to resemble a firefly (and hence the ship class' name).

Captain Malcolm "Mal" Reynolds and his first mate Zoe are veteran "Browncoats" of the Unification War in which they attempted to resist the Alliance. The Alliance is an organization of "core" planets that succeeded in forcibly unifying all of the colonies under a single government. Although the central planets are well under Alliance control, the outlying planets and moons resemble the 19th-century American West, with little government authority. Settlers and refugees on the outlying worlds enjoy relative freedom from the central government, but lack the amenities of the high-tech civilization on the "core" worlds. After the loss of the war, Mal bought the spaceship Serenity to scrape together a way of life for himself and his crew by making cargo runs and performing other tasks, legal or otherwise.

Featuring a blend of elements from the space opera and western genres with a bit of Robin Hood and his Merry Men, the show depicts mankind's future in a way that is uncharacteristic of many contemporary science fiction programs. Unlike most traditional space operas, there are no alien creatures or space battles. Firefly takes place in a multi-cultural future, where the divide between the rich and poor is great. Chinese is a common second language for many people; it is used in advertisements, and characters in the show frequently use Chinese words and curses (pronounced with a varying degree of accuracy). According to the DVD commentary on the episode Serenity, this is explained as being the result of China and the United States becoming the two superpowers that expand into space. This Sino-American allegiance is supported by close examination of labels on the crates from the episode "The Train Job", where crates of Alliance goods are marked with a Chinese flag superimposed over a United States flag. An interesting intrusion of Japanese is noted in the form of katakana script throughout the television series and the film.

For fans, the dialogue and interplay between characters is central to the charm of the show, resulting in stories that are alternately serious and humorous. The show's visual style also differs from contemporary shows in that camera shots are often handheld, with deliberately misframed or out-of-focus subjects, in an attempt to give scenes an immersive and immediate feeling; computer-generated scenes mimic the motion of a handheld camera. Exterior shots of action taking place in the vacuum of outer space realistically lack sound effects, an approach that stands in contrast to many science fiction films and television series.

- From Wikipedia