In television and radio programming, a serial is a show that has a continuing plot that unfolds in a sequential episode-by-episode fashion. Serials typically follow main story arcs that span entire television seasons or even the complete run of the series, and sometimes spinoffs, which distinguishes them from episodic television that relies on more stand-alone episodes. Worldwide, the soap opera is the most prominent form of serial dramatic programming. In the United Kingdom, the first serials were direct adaptations of well-known literary works, usually consisting of a small number of episodes.

Serials rely on keeping the full nature of the story hidden and revealing elements episode by episode, to encourage spectators to tune in to every episode to follow the plot. Often these shows employ recapping segments at the beginning and cliffhangers at the end of each episode.

The invention of recording devices such as VCRs and DVRs along with the growing popularity of streaming services has made following this type of show easier, which has resulted in increased success and popularity. Prior to the advent of DVRs, television networks shunned serials in prime time as they made broadcast programming reruns more difficult and television producers shunned them because they were tougher to go into broadcast syndication years down the road.

Serials contrast with episodic television, with plots relying on a more independent stand-alone format. Procedural drama television programs are commonly episodic, sometimes including a serial subplot.

Shorter serial programs known as telenovelas (and earlier, radionovelas), originating and often produced in Spanish- and Portuguese-speaking Latin America, have become popular worldwide.

The term "serial" refers to the intrinsic property of a series – namely its order. In literature, the term is used as a noun to refer to a format (within a genre) by which a story is told in contiguous (typically chronological) installments in sequential issues of a single periodical publication.

More generally, "serial" is applied in library and information science to materials "in any medium issued under the same title in a succession of discrete parts, usually numbered (or dated) and appearing at regular or irregular intervals with no predetermined conclusion."

The term has been used for a radio or television production with a continuously evolving, unified plot and set of characters, spread over multiple episodes. In the United States, daytime soap operas have long had a serial structure. Television mini-series also commonly come in a serial form. Starting in the mid-1970s, series with soap opera-like stories began to be aired in prime time (e.g. Dallas, Dynasty). In the 1990s, shows like The X-Files and The Sopranos began to use a more serial structure, and now there are a much wider range of shows in serial form.