The life cycle of U.S. television shows

Television production companies either commission teleplays for TV pilots or buy spec scripts. Some of these scripts are turned into pilots. Those which the production company thinks might be commercially viable are then marketed to television networks—or television distributors for first-run syndication. (KingWorld

Networks sometimes preemptively purchase pilots to prevent other nets from controlling them, and the purchase of a pilot is no guarantee that a show will get an order for more episodes. Those that do get " picked up" get either a full or partial-season order, and the show goes into production, usually establishing itself with permanent sets, a full crew and production offices. Writers are hired, directors are selected and work begins, usually during the late spring and summer before the fall season-series premieres. (Shows can also be midseason replacement, meaning they are ordered specifically to fill holes in a network schedule created by the failure and cancellation of shows which premiered in the fall. Buffy the Vampire Slayer and The Office are examples of successful midseason replacements.)

The standard broadcast television season in the United States is 22 episodes per season; sitcoms may have 24 or more; animated programs may have more (or fewer) episodes; cable networks with original programming seem to have settled on about 10 or 12 episodes per season, much in line with British television programming.

American soap operas air in the afternoon, five days a week, without any significant break in taping and airing schedules throughout the year. This means that these serials air approximately 260 episodes a year, making their casts and crews the busiest in show business. These shows are rarely, if ever, repeated, making it difficult for viewers to " catch up" when they miss programming. However, cable channel SOAPnet provides weekly repeats for some broadcasts.

Networks use profits from commercials run during the show to pay the production company, which in turn pays the cast and crew, and keeps a share of the profits for itself. (Networks sometimes act as both production companies and distributors.) As advertising rates are based on the size of the audience, measuring the number of people watching a network is very important. This measurement is known as a show or network's ratings. Sweeps months (November, February, May, and to a lesser extent July) are important landmarks in the television year — ratings earned during these periods determining advertising rates until the next sweeps period, therefore shows often have their most exciting plot developments happen during sweeps.

Shows that are successful with audiences and advertisers receive authorization from the network to continue production, until the plotline ends (only for scripted shows) or if the contract expires. Those that are not successful are often quickly told to discontinue production by the network, known as cancellation. There are instances of initially low-rated shows surviving cancellation and later becoming highly-popular, but these are rare. For the most part, shows that are not immediately or even moderately successful will be cancelled by the end of November sweeps. Usually if a show is canceled, there is little chance of it ever coming back again especially on the same network it was canceled from; the only show in the US to ever come back from cancellation on the same network is Family Guy. However, canceled shows like Scrubs, Southland, and Medium have been picked up by other networks, which is becoming an increasingly common practice.

Once a television series reaches a threshold of approximately 88 to 100 episodes, it becomes a candidate to enter reruns in off-network syndication. Reruns are a lucrative business for television producers, who can sell the rights to a " used" series without the expenses of producing it (although royalties may need to be paid to the affected parties, depending on union contracts). Sitcoms are traditionally the most widely syndicated reruns and are usually aired in a five-day-a-week strip. Marginally performing shows tend to last less than five years in broadcast syndication, sometimes moving to cable channels after the end of their syndication runs, while more widely successful series can have a life in syndication that can run for decades (I Love Lucy, the first series designed to be rerun, remains popular in syndication sixty years after its debut). Cable networks and digital broadcast channels have provided outlets for programming that either has outlived its syndication viability, lacks the number of episodes necessary for syndication, or for various reasons was not a candidate for syndication in the first place. Popular dramas, for instance, have permanent homes on several basic cable channels, often running in marathons (multiple episodes airing back-to-back for several hours), and there are also cable channels devoted to game shows (Game Show Network), soap operas (the soon-to-be-defunct SoapNet), Saturday morning cartoons (e.g. Boomerang) and even sports broadcasts (ESPN Classic). Most reality shows perform poorly in reruns and are rarely seen as a result, other than reruns of series still in production, on the same network on which they air (almost always cable outlets), where they air as filler programming.