Television is a business like any other. The goal is to make money, not entertain the masses. Television – tele –far, vision -sight Someone has an idea for a tv show and pitches it to an executive at a network or cable company. If there is interest (most ideas are rejected) a pilot is produced by a tv production company. http://www.cbc.ca/dragonsden/2012/10/gotta-grudge.html After production, the show is turned over to the television network, which sends it out to its affiliate stations, which broadcast it in a specific time slot. A pilot is the first episode of a show -- they're shot, fittingly, during pilot season, between January and May. If the network likes the pilot, it will pick up the show for the season and make it a series. During development season, a broadcast network will buy 25 comedy scripts, shoot 12 of them as pilots and pick up two of the pilots for a series. A “series", is a connected set of television program episodes that run under the same title, possibly spanning many seasons. A new series is often ordered (funded) for just the first 10 to 13 episodes, to gauge the audience interest. If it is "picked up", the season is completed to the regular 20 to 26 episodes. The term "midseason replacement" usually refers to an inexpensive short-run (10–13 episode) show designed to take the place of an original series that failed to garner an audience and has not been picked up. The job of the director of network programming is to gauge constantly shifting and fragmented audience tastes to build a morning, daytime and primetime TV schedule that draws the most viewers possible. They must identify good show ideas, buy them and invest the money and resources to turn the idea into a highly marketable, successful TV program. A good show has higher ratings, better advertising sales and thus makes more profit for the company. If the shows on one network consistently get lower ratings than shows on another network, advertisers might decide to take their business elsewhere. http://www.nielsen.com/us/en/insights/top 10s/television.html Nielsen ratings tell potential advertisers how many people watch a specific show broken down by age and sex within a geographical are or market. This is done through set meters connected to televisions in selected homes. These small devices gather the viewing habits of the home and transmit the information nightly to Nielsen through a "Home Unit" connected to a phone line. Another method is through a select representative sample of viewers filling out in-depth diaries of their viewing behaviour. If the Nielsen ratings are good, the show is kept alive as long as possible. If not, the show is usually canceled. The show's creators are then left to shop around remaining episodes, and the possibility of future episodes, to other networks. http://www.angelfire.com/trek/proutsy/ - long running tv shows http://www.yourtv.com.au/slideshow/120147/tv-shows-that-came-back-fromthe-dead.slideshow Syndicated shows -- shows that have successfully run on the networks and are subsequently sold in package deals to local stations and possibly other networks. (minimum 100 episodes) For DVD distribution, distributors release the first half of the season in stores just before the second half first airs to increase interest in the season's second half. http://articles.latimes.com/2010/apr/04/entertainment/la-ca-cablecosmology4-2010apr04 - great article about broadcast vs cable