A television program (television programme in the United Kingdom, Ireland and many Commonwealth countries) or television show is a segment [?seɡm(xù)?nt](部分) of content broadcast on television. It may be a one-off [?w?n??:f, -??f](一次性) broadcast or part of a periodically [p??r???d?kl?](周期性地)recurring television series.
A television series that is intended to be broadcast a finite [?fainait](有限的) number of episodes(集) is usually called a miniseries or serial (although the latter term also has other meanings). A short run lasting less than a year is known in the United States and Canada as a season and in the United Kingdom and (not necessarily) the rest of the PAL countries as a series. This season or series usually consists of 15–26 installments(部分) in the United States, but in the United Kingdom there is no defined length. United States' industry practice tends to favor longer seasons than those of some other countries.
A single instance [?inst?ns](例子) of a program is called an episode, although particularly in the USA this is sometimes also called a "show" or "program", and in Great Britain and Ireland a "programme". A one-off broadcast may, again particularly in the USA and USA-influenced countries, be called a "special", or particularly in the UK a "special episode". A television movie or in the UK a television film ("made-for-TV" movie) is a film that is initially broadcast on television rather than being released in cinemas or direct-to-video, although many successful television movies are later released on DVD.
Today, advertisements play a role in most television programming, such that each hour of programming can contain up to 15 minutes of advertisements in some countries. By contrast, being publicly funded, the British Broadcasting Corporation (BBC) in the United Kingdom does not run advertisements, except totrail [treil](跟蹤) its own programmes. Its promotions appear between and near the end of programmes but not in the middle of them, much like the Public Broadcasting Service (PBS) in the United States and the Australian Broadcasting Corporation (ABC) in Australia. The number of commercial interruptions(中斷) is also vary, for instance Japanese television tends to prefer fewer and longer commercial breaks while American television has several spread throughout the program. This has an impact on the writing of the show; in order to provide a smooth transition as well as keep the audience [??:dj?ns，???di?ns](觀眾)from switching channels